


For Science!

by grimm, Tsuminoaru



Category: Teen Wolf (TV)
Genre: Alternate Universe - College/University, Alternate Universe - Werewolves Are Known, Craigslist, Dubious Consent, Heat bonds, M/M, Mating Cycles/In Heat, POV Multiple, Pining
Language: English
Status: Completed
Published: 2014-08-22
Updated: 2014-08-22
Packaged: 2018-02-14 05:32:39
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 5
Words: 35,959
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2179839
Author URL: https://archiveofourown.org/users/grimm/pseuds/grimm, https://archiveofourown.org/users/Tsuminoaru/pseuds/Tsuminoaru
Summary: <blockquote class="userstuff">
              <p>From his textbooks, Stiles had gotten the impression that vampires had a weird, stretched out look to them — slightly too-long limbs and pale skin. This guy, though, he looked human, broad-shouldered and clearly muscular even under a loose sweatshirt. He wasn’t pale at all, his skin lightly tanned, hair dark, eyes pale. They narrowed at Stiles and Stiles froze as the man looked him up and down, clearly judging him. He must have passed the test, though, because the man kind of shrugged and said, “Take off your clothes.”</p>
            </blockquote>





	1. Chapter 1

**Author's Note:**

> This piece is a collab! Grimm did the fic, Tsumi did the art!
> 
> This fic is based off [this idea](http://jerakeenc.tumblr.com/post/63462110034/stiles-is-studying-supernatural-culture-and-its). I never asked if it was okay to write it so, uh, here's hoping it is. Many thanks to [Jo](http://blacktofade.tumblr.com/) & [Ro](http://rrrowr.tumblr.com/) for their beta skills! Thanks to [Shannon](http://emilysgilmores.tumblr.com/) for coming up with the super classy term "gaper."
> 
> WARNING: Dubious consent for the first sex scene (see notes at the end of fic for clarity/spoilers). There's a very brief semi-graphic Stiles/Deucalion scene (also a mention of Stiles/Allison? Boy gets around). There's also some vague ABO in this, but it only applies to werewolves.
> 
> (Also forgive me guys, science was not my thing in school and Ro tried to help but I'm pretty much useless, so go easy on all Stiles' research and papers because I literally don't know what I'm talking about.)

Stiles absently tapped his fingers against his desk as he watched Professor Fenris walk up and down the rows, handing out papers. Stiles' mind was already back in Beacon Hills for the long Columbus Day weekend. Scott was coming back from Sacramento and they were planning a huge bonfire. He was looking forward to a couple nights of debauchery.

Stiles, already in his third year at college, was bored. Junior year was proving itself no more difficult than the first two. Professor Atkins, who was the head of the Supernatural School, told him a couple of weeks ago that he had a likely future with the government, which was exactly what he wanted; he had long-term plans to join the FBI. Scott told him that he'd be bored out of his mind, that he watched too much _X-Files_ , but Stiles sincerely doubted that; with a degree in Supernatural Studies, how the fuck could life be boring?

Professor Fenris passed by his desk, handing Stiles his paper without a second glance. Stiles gave his grade the most cursory of looks — he hadn't gotten lower than a B+ in any supernatural-related class since ninth grade — then did a double take. C-, the paper said, with Professor Fenris' chicken-scratch below: _Your theory is sound, but your lack of hands-on experience shows._

For a moment, all Stiles could do was gape at his paper, all the noise in the room slowly filtering away until all that was left in his head was a dull pounding. A fucking C. A fucking C _minus_. How fucking _dare_ Fenris? Hands-on experience — fuck that. Scott was a werewolf. Lydia was a banshee. He'd seen all sorts of weird things dragged into the sheriff's station. Hands-on experience his ass.

People filtered out of the classroom around him, but instead of following, Stiles walked to the front of the classroom and stopped in front of Fenris' desk.

"Mr. Stilinski," Professor Fenris said, pulling on his coat. "Can I help you?"

"I want to talk to you about my grade," Stiles said tightly, anger making him curt. "I don't think I — "

"Deserve it?" Fenris quirks an eyebrow at Stiles.

"I worked hard on this paper!" Stiles protested.

"Did you?" Fenris leveled him with a long look. "Tell me, Mr. Stilinski, when you were in high school, how hard did you study before a test?"

"I — " Stiles was caught off guard. "As hard as anyone, I guess."

"And now, when you have papers to write and tests to take, do you spend hours studying in the library?"

"I guess," Stiles said with an angry shrug. "What — "

Fenris blinked calmly at him. "And what was the topic of your paper?"

Stiles ground his teeth together before answering, "Physiological differences between the East and West Atlantic mermaids and the impact that makes on their breeding habits."

"And?" Fenris prompted. Stiles stared at him, unsure what he was looking for. Fenris sighed. "Did it ever occur to you to contact the Marine Biology department and see if they have specimens in their collections? To go to the aquarium and see them breeding yourself? Books can only take you so far in this field, Mr. Stilinski. To be able to talk intelligently about your subject, you must _know_ your subject."

"But — no one ever _told_ me," Stiles protested.

"Then you need to learn to think for yourself," Fenris scolded. Stiles scowled. "The FBI doesn't want scholars. Mr. Stilinski; they want thinkers, doers. I hope this has been helpful," he added, picking up his bag and turning on his heel. Stiles glowered after him, though he quickly wiped the look from his face when Fenris paused in the doorway. "Mr. Stilinski," he added thoughtfully, "we're moving onto bipeds next. You might consider vampires for your next essay topic."

-

When Stiles came through the door to his apartment, he found Erica slumped across the couch in the living room, grinning sharply.

"What?" Stiles asked suspiciously.

"Isaac said you threw a hissy fit about your anatomy essay grade," Erica replied, pretending to pout sympathetically. "Poor baby."

Stiles scowled at her, slinging his backpack onto the floor. "I didn't throw a hissy fit," he retorted, trying to sound dignified. "I talked to Fenris about my grade, that's it."

Erica batted her long lashes at him. "And what did he say? Did you offer to suck his dick for a better grade?"

"Fuck you," Stiles grumbled, heading into the kitchen. "He said I need hands-on experience."

"Ooh," Erica said, brightening. "You could come volunteer at the shelter — "

"I am _not_ working at that weirdo 'animal' shelter," Stiles said, coming back into the living room with a beer. "Last time I went with you, I got bitten by a leprechaun and had boils for a week."

Erica giggled. "That was hilarious."

"Says you," Stiles retorted moodily, picking up the remote and flicking on the television.

"You could study Boyd," Erica offered, still giggling.

Stiles rolled his eyes. "I am _not_ studying your boyfriend, thanks."

"So what are you going to do, then?"

Stiles took a long pull at his beer, tapping his fingers against the glass. "I don't know," he finally replied. "Fenris suggested I do vampires for my next topic, and where the hell am I going to find one of those, huh? It's not like I can go to the zoo."

"No," Erica agreed, sounding thoughtful. Stiles settled himself back into the cushions, feeling out of sorts. He knew, objectively, that he was being a big baby about this, but the conversation with his professor had thrown him. "There is something you can try," Erica added slowly.

Stiles looked over at her, raising his eyebrows. "Yeah?"

"Craigslist."

Stiles' face dropped back into a scowl. "You're joking."

"I'm not!" Erica protested. "You know how there's that whole casual encounters section? Well, there's a section just like that, but for meeting supernatural peeps."

"I'm not going pick a vampire up off Craigslist!" Stiles argued. "I'm not looking for sex — "

"It's not about sex!" Erica said, waving her hands irritably. "It's for what they _do._ There are really weird people out there, Stiles, people who are into getting their blood sucked by a vampire, or their life-force drained by a succubus!"

"I don't want to die, either!" Stiles snapped.

"You won't die, you big baby," Erica sighed, rolling her eyes. "They just take a little bit."

Stiles narrowed his eyes at her, suddenly suspicious. "Is that where you met Boyd? You tell everyone you met while working at Gap, but seriously — "

"Oh my god," Erica groaned, getting to her feet. "I'm going to go make burritos and pretend I didn't hear that."

"Why, cause it's true and you don't want to admit it?" Stiles shouted after her. "Your creepy secret's safe with me!"

"I'm putting cilantro in half your burrito!" Erica hollered back. "And I'm not telling you which half!"

_"Evil,"_ Stiles gasped, sinking in the couch, truly wounded.

-

Despite the fact that it was incredibly weird and he was totally creeped out by the idea, Stiles was also an insatiably curious person, which was why he found himself surfing Craigslist after dinner (a cilantro-free dinner, because Erica might be evil but she wasn't the _devil)_. Stiles found himself simultaneously enjoying himself and horrified — he'd never really gone trawling through the depths of Craigslist, except maybe to laugh over missed connections with Scott a couple of times.

This, though — this was _hardcore_. Stiles had never been aware that there were so many people in the world so eager to dance with nymphs and bear the demon children of cults and get knotted by werewolves. He spent nearly an hour clicking link after link, utterly entranced by the new facet of supernatural culture shining before him. He stared at a set of dick pics posted by an incubus — it was possibly the nicest dick he'd ever seen — for way too long before clicking out of the posting. Erica hadn't been entirely right; not _all_ the listings were about sex, only the vast majority. Some of the writing in them was so explicit it made Stiles' ears burn.

Erica came into his room as Stiles sat at his desk, flipping through a couple of ads from vampires he'd tabbed. "You give into your desires?" she teased, flopping down onto his bed.

Stiles shot her a dirty look over his shoulder and retorted, "Just picking through your sloppy seconds." Erica threw a pillow at him and he ducked, laughing.

"You know," Erica said abruptly, giving him a sly look. "I've heard stories about people being bitten. If it's not forced, you get a feeling of euphoria that's so strong some people have _died_ of ecstasy."

Stiles rolled his eyes. "You don't die of happiness, Erica, you die of blood loss."

Erica ignored him and continued happily, banging her heels against the mattress, “I’ve heard that some people orgasm when they get bitten, and some of them come so hard they have _brain aneurysms.”_

“You sound way too happy about that,” Stiles replied. “Are you trying to get rid of me? Just say the word and I’ll move out; you don’t have to kill me.”

Erica cackled, but didn’t respond, which was a little worrying.

Stiles drummed his fingers against his desk, staring at the screen. He had three ads still pulled up; they were the only ones with proper grammar that _didn’t_ sound like serial killers (although being vampires, how could you tell, really?). And he was thinking about contacting them, honestly considering it.

“Is this legal?” he asked abruptly, an image of his father, small-town sheriff coming into his head. His dad would kill him if he got caught soliciting a — well, it wasn’t like he was buying a prostitute, but still.

“I think so,” Erica replied. “From what I hear, the police don’t care as long as no one dies and no money gets exchanged.”

“Good,” Stiles said. “I’m broke.”

She smirked at him. “Too poor to even leave a tip?”

Stiles dragged his hands across his face. “Are you supposed to tip? Jesus, I don’t _know_ anything about this.”

“Relax,” Erica sang, rolling onto her stomach. “Just contact someone. Odds are they’ve done this before and can answer any and all of your questions.”

“You’re the one who told me about this stupid thing,” Stiles grumbled, copying the email address posted in one of the listings into a new email draft. “Look, if I end up a dried-out husk because some vampire got a little overzealous, it’s your fault.”

“Just be sure to write out your will before you go,” Erica replied solemnly. “Make sure you leave me all your books.”

Stiles smirked at her. “No can do, already promised them to Lydia.” He paused, staring at the screen, cursor blinking in the empty email.

“Are you going to do it?” Erica asked quietly.

“I…think so,” Stiles said, though he still wasn’t certain. But hey, an email wasn’t binding. He could talk to a vampire, get some more info — it couldn’t hurt. He could always change his mind. He took a deep breath. “Yeah. Yeah, I’m gonna do it.”

“Better start loading up on spinach,” Erica cackled. “Those bloodsuckers need their iron too.”

-

A little more than a week later found Stiles pacing back and forth outside of a crappy motel out on the edge of the city near the airport. He’d sent emails to three different vampires, then immediately left for Beacon Hills, determinedly not checking his email the entire time he’d been home (the weekend had been _excellent_ , even if Scott had spend half the time checking his phone and bemoaning the fact that Lydia hadn’t come home. Stiles had had to remind him that cross-country plane tickets weren’t cheap and since Lydia’s parents had cut her off after spending ten thousand dollars at the New York Fashion Week, she had to count her pennies).

When he’d gotten back into the city, Stiles had checked his email to find that only one of the vampires had replied — a man by the not-at-all-suspicious name of John Smith. Despite the obvious pseudonym — which didn’t really calm Stiles’ worries about the questionable legality of the whole thing —

 the whole thing was simple enough; they’d meet in the hotel, John would suck a little bit of blood from anywhere Stiles chose, and that was it. John would leave and Stiles thought he’d stay and watch some HBO or something. This was probably the kind of place where you paid by the hour, but he’d rather be out of the house tonight because it was the full moon, which meant Boyd was coming over and Stiles did _not_ want to hear the sounds coming out of Erica’s room he’d heard on the last full moon. Shitty hotel sheets and _Boardwalk Empire_ reruns were well worth avoiding more mental scarring.

“Okay,” Stiles said, gathering up his nerves. He sent a text to Erica that said, _In case I don’t come back_ , followed by the address of the motel, and stepped into the lobby. It was nicer than it looked from the outside, which relaxed him a little, and he walked up to the desk, where a bored-looking woman sat in front of a computer.

She gave him the most cursory of glances before looking back at her screen. “You got a reservation or do you need a room?”

“Uh,” Stiles said, remembering the instructions from the email. “Um. There’s a reservation. Under John Smith.”

Her long acrylic nails clattered against the keyboard for a moment before she looked up at him, raising one drawn-on eyebrow. “There are three reservations under that name.”

“Oh,” Stiles said blankly. “Uh.” He didn’t have any other information — not even a phone number. God, why did the dude go with _John Smith?_ Why not have _fun_ with his fake name? Even Dr. Acula would have been better. “Uh, I don’t know. Choose one.”

The woman gave him another long look, but clearly didn’t care enough because her nails clacked against the keyboard once more, then she slid a keycard through a scanner and passed it to him. “Checkout’s at eleven,” she announced vaguely, eyes already slipping back to the computer screen. Stiles glanced into the mirror behind the front desk. He could see she was looking at recipes on Pinterest.

“Thanks,” Stiles told the top of her head and headed for the elevators.

The hotel room was small, just a queen-sized bed, a bureau, and a television, and it smelled faintly of mold, but the mattress was comfortable enough, and there were free peanuts. Stiles ripped the bag open and popped one after another into his mouth to distract himself from his growing anxiety, flipping through the channels on the TV. He wondered where he should have the vampire bite him — he’d been relieved to find out that it didn’t have to be his neck, because that would have been an awkward thing to explain at school on Monday.

Stiles had just decided on his ribs when there came the sound of a card being swiped through the reader on the door. He sat up quickly, all his nerves swelling with tension as the door swung open. “Hi,” he said, talking quickly to cover his anxiety. “I ate all the peanuts, sorry. I figured I’d need the extra energy — “

Stiles stopped talking as John Smith stepped into the room. From his textbooks, Stiles had gotten the impression that vampires had a weird, stretched out look to them — slightly too-long limbs and pale skin. This guy, though, he looked human, broad-shouldered and clearly muscular even under a loose sweatshirt. He wasn’t pale at all, his skin lightly tanned, hair dark, eyes pale. They narrowed at Stiles and Stiles froze as the man looked him up and down, clearly judging him. He must have passed the test, though, because John kind of shrugged and said, “Take off your clothes.”

Stiles hesitated, watching John unzip his hoodie. Getting naked hadn’t been mentioned in any of their earlier communications, but maybe it was a way of getting them comfortable around each other. Which — okay. It was weird, but Stiles was new to this whole world. Maybe it was standard. He could hear Dr. Fenris’s voice in his head, lecturing him about experience. He couldn’t assume anything here.

So he slipped off his shirt and undid his belt, shimmying out of his pants. He hesitated again over his underwear, but John didn’t, pushing down his own dark boxer-briefs. Stiles swallowed at the sight of John’s cock, half-hard between his legs. It hadn’t really occurred to Stiles before, but how did vampires get erections if they didn’t have a pulse — no blood to rush to the penis? Maybe John would be willing to stick around for a Q & A afterward, though maybe not — he looked like the impatient type. Suck ‘em and run, or whatever.

John looked at Stiles, raising an irritated eyebrow, and Stiles hurriedly shoved down his underwear, kicking them to the floor. Oh, fuck, his dick was stirring too. This wasn’t supposed to be sexual, but John was really fucking hot — way hotter than any guy Stiles had ever slept with — and he hadn’t been _planning_ on sex but hell, he was only human. He’d slept with strangers before; he’d gone through a period in sophomore year where he’d gone home with someone new almost every weekend — but he’d usually had at least half an hour of conversation or a couple of drinks first. He wished, now, that he’d at least had a beer to soothe his nerves, but John had been explicit about no alcohol — it thinned the blood too much or something and Stiles wasn’t keen on dying tonight.

“On your knees,” John said, taking a step toward the bed. Stiles’ eyes flickered down to his dick before he turned, nervously licking his lips as he braced himself on his hands and knees.

“Hey, uh, can I just ask?” Stiles said hesitantly, feeling the bed dip as John knelt behind him. “What’s your name? Because John’s my dad’s name and I feel really weird about — ”

“Derek.”

“Okay,” Stiles said. “Thanks.” God, he was fucking _hard_ , his dick pulsing, jumping with every nervous breath. He hoped it wasn’t like, an insult or something. Stiles thought about what Erica had said, about the possibility of orgasming at the bite. He was pretty sure it was going to happen, and probably sooner rather than later.

Behind him, the mattress sunk lower as John — no — _Derek_ moved in. Stiles could feel the heat of his body and that was weird for a vampire, right? Stiles couldn’t help but jolting a little at the touch of Derek’s hands on his thighs, warm fingers brushing against his hipbones. “You’re not ready,” Derek said, sounding irritated.

“Huh?” Stiles replied. “I did n — _oh.”_ The only warning he got was a hot sigh of air against his skin and then fuck, fuck, fuck, that was Derek’s _mouth_ on his _ass_. Those were Derek’s big hands spreading Stiles’ ass-cheeks open, his tongue licking wet lines across his skin. This was so far from anything Stiles had expected — he hadn’t even _showered_ since this morning — that for a long moment all he could do was try to connect the dots in his brain. A difficult fight, it turned out, because Derek possessed a fucking talented tongue and white-hot sparks of pleasure kept skipping up Stiles’ spine, making his toes curl, unconsciously pushing back, seeking more.

He was getting a rimjob from a vampire. A fucking _vampire._ He — Stiles lifted his head abruptly, mouth slackening in realization even as Derek pressed a finger inside him, punching a moan from his loose lips. Stiles was almost one hundred percent sure he’d gotten the wrong John Smith. There’d been nothing, _nothing_ , about sex in the email exchange and from the way Derek had jumped right in, this had to have been planned. Jesus, and here was Stiles, trusting, idiotic Stiles, who’d been happy to strip naked without questioning it and now he had a man-shaped creature of undetermined supernatural nature with two fingers inside him. Stiles panted out a rough laugh. Just wait until Erica heard about this.

Erica, he thought, his eyes slipping sideways to the window. Boyd. Stiles hadn’t closed the curtains and he could see the moon hanging full and silver in the sky outside. Oh. _Oh._ There had been a _lot_ of werewolves putting up ads for the full moon. Apparently getting knotted was something that a lot of people were into. Stiles hadn’t given it much thought.

Despite the fact that his best friend was a werewolf, Stiles didn’t actually know that much about them. Scott had been bitten back in high school and he’d dug in his heels when the local pack had offered him space amongst their ranks. He didn’t follow any sort of werewolf behavioral norms so as far as Stiles knew, all his knowledge of werewolves was atypical. Stiles had never talked to him about his sexual behaviors — partly because he didn’t want Scott to feel like a science experiment and partly because he just really didn’t need to know those sort of intimate details about his best friend. What he did know was mostly rumors, because they’d only just started the unit on werewolves and hadn’t reached anything on reproductive behavior yet.

Stiles was in over his head. He knew that. What he didn’t know was how the heat affected Derek — how in control of himself he was. Stiles had to say something.

“Derek,” he tried — gasped. His mouth felt like a desert. “I — “ Derek rumbled low behind him; Stiles could feel his tongue working around his fingers and the noise vibrated through him, rolling up his spine. “Fuck, I — ” But he couldn’t get it out. Some treacherous part of his brain assured him that no, this was going to be good, really, and maybe he was desperate, or maybe he was just stupid, but what he managed to say was, “I’m Stiles.”

Derek made another low noise, one which Stiles had no idea how to interpret. Stiles felt the bed shift as Derek sat back on his heels, his hand falling away, and Stiles felt the loss of him intimately, his hips hitching back almost unconsciously in an attempt to reconnect. But Derek leaned away from him and over the side of the bed to pull a packet of lube out of his jeans and Stiles took the opportunity to bend his head and look at Derek’s face, at the grim, irritable set of his mouth and his flushed cheeks. Stiles wondered if he was embarrassed, or angry, or — was it possible that this was Derek’s first time doing this and he was floundering just as badly as Stiles?

It didn’t seem likely, considering the confident way he’d come into the room and told Stiles to strip, but then another possibility occurred to Stiles and his stomach dropped with nerves and anticipation. _Heat._ They hadn’t covered it in class yet, but it was one of the biological imperatives that even Scott couldn’t ignore — an hours-long — or even days long — burning need to procreate.

Stiles took a deep breath to keep himself from panicking, twisting his head away as Derek leaned toward him. There came the touch of Derek’s fingers at Stiles’ entrance, slick and cool, and Stiles jolted in shock, his hips jerking forward. _This is happening,_ he thought wildly, a little frantically. He could stop this, he was sure, but he wasn’t sure he wanted to. The longer he stayed, the more Derek touched him, the better he felt, a golden haze creeping in at the corners of his mind. He was adaptable.

Derek moved quickly, his gestures abrupt and impatient though he still worked Stiles open with some care, one hand on his hip holding Stiles in place, the other stretching him wide. If Stiles looked between his legs he could see Derek’s thighs, taut and muscular, and his cock between, thick and flushed red. His own dick was hard and leaking, tapping against his stomach every time Derek made him jump.

Stiles’ thighs were shaking, his mind heavy and blurred with need. His body felt as though it were on fire; he sobbed when Derek pulled away, mouth opening to beg, “Please, c’mon, _fuck me.”_

Derek made a low noise, hungry and impatient, and he shifted behind Stiles, rising onto his knees. Stiles shuddered as Derek settled in, his hands at Stiles’ hips, pressing inside him with one push. Stiles cried out at the feel of him, his fingers curling in the sheets, back bowing. Derek exhaled, the force of his breath ruffling Stiles’ hair, but he didn’t wait before he began to move, starting with a short roll of his hips that had Stiles gasping, dropping onto his elbows so he could press back. Derek seemed to like that — he growled, anyway, and Stiles chose to take that as approval. He gripped harder at Stiles’ hips, fingers digging in so deep Stiles knew he’d be waking up with bruises.

“You feel so fucking good,” Stiles muttered, forehead pressed to the comforter. He wasn’t usually much of a talker in bed, especially not with strangers, but there was that haze in his head and everything felt _right_. More than right, really — _great._ Derek felt great and he deserved to know it.

Derek seemed to like that too; he shifted forward, pressing his chest to Stiles’ spine, bringing one hand forward to brace himself next to Stiles’ head. Stiles stared dazedly at the corded muscle on his forearm, breath hitching with every thrust of Derek’s hips, moaning sharply when Derek licked at his neck, teeth just grazing his skin before his mouth migrated toward Stiles’ shoulder.

It was good, so fucking good — Stiles’ head was fogged with pleasure. It made him heavy-limbed and golden-tongued, lavishing Derek with praise and soft, hitching moans with every thrust. He’d never felt so good, his entire body alight and singing with electricity. He wanted Derek to lose control, really _fuck him_ , and maybe he said that out loud because Derek snarled and shifted backward, settling onto his heels.

He pulled Stiles with him, one arm looped over his chest, the other gripping his hip, holding him upright effortlessly. Stiles moaned at the new position; Derek struck deeper inside him now, giving him barely a moment to adjust before he was moving again, faster this time, jolting Stiles with every thrust — and it felt fucking amazing. Just knowing how strong Derek was — Stiles had no doubt that he could break every one of Stiles' bones without breaking a sweat — and fuck, there was nothing stopping him. Stiles didn’t know if Derek was even in control or not.

_"Fuck,"_ Derek growled, driving up into him relentlessly. Stiles could _feel_ him starting to swell, his knot growing as he neared orgasm. It was a strange sensation, the knot catching at Stiles' rim with every thrust of Derek's hips. Stiles moaned, fighting the urge to clench down against the intrusion. "Relax," Derek panted, brushing his lips against Stiles' ear. Stiles made a soft noise at Derek's touch, turning his head for better access, and Derek took the invitation, biting down at the junction of Stiles’ neck and shoulder. Stiles let out a low cry of shock because it _hurt_ and he could feel wetness on his neck — saliva? _Blood?_ — and fuck fuck fuck he didn’t even know if Derek was an alpha or not.

Derek didn’t even slow down, his thrusts verging on the edge of painful as his knot grew, pain zipping up his spine to fizzle into an odd blurred sense of pleasure. Stiles, tears burning in the corners of his eyes, reached back with one hand, blindly gripping at Derek’s hair and Derek's movements stuttered for just a moment at Stiles’ touch before he thrust again — once, twice more before his knot grew too large to slip back out and they were locked together.

"Oh my god," Stiles mumbled, chest heaving. He'd never felt so _full_ before, flooded with golden warmth. He hurt all over yet he needed more, needed — "Fuck, can you — I need — "

"Demanding," Derek remarked, sounding a little punch-drunk, but he obligingly let go of Stiles’ hip and wrapped a hand around Stiles’ dick, flushed angry and red and weeping precome. Stiles groaned, open-mouthed, fighting for traction so he could thrust into Derek's hand, but Derek remained in control, the arm around his chest solid and unmoving as an iron bar, his fingers tense against the base of Stiles’ throat. Derek’s chest slipped against Stiles' sweat-slicked back as he began rolling his hips again, shallow thrusts that had his cock hitting Stiles' prostate with every movement.

"Fuck," Stiles murmured, heating pooling in his groin, toes going numb as his orgasm hit. "Fuck, _fuck!"_ Derek fucked him through it, Stiles open-mouthed and almost sobbing as he came, spine bowing. Derek kept his hand on Stiles until Stiles was shuddering, over-stimulated and flooded with heat, before he shifted again, pressing Stiles back down into the mattress and fuck, if Derek had been rough before he was relentless now, pounding into Stiles without grace or rhythm as he sought his own release. It hurt in the best way possible, pain jangling up Stiles’ spine, blending with his pleasure in a way that made him desperately wish he hadn’t already come.

Derek bent over him, one hand gripping at the headboard, the other clutching so hard at Stiles’ hip he knew he’d bruise, snarling wordlessly as he fucked into Stiles. Stiles went very still, still open-mouthed and gasping, because there was pain at his hip, sharp pinpricks, and above his head there was a splintering sound — Derek had fucking _shredded_ the wooden headboard. He lifted his head very carefully and saw the deep lines scored into the woods and the way the tips of Derek’s fingers had gone wickedly pointed and he breathed in sharply.

But even as he watched, Derek’s claws melted back into blunt fingernails and his hand pulled away from the headboard, dropping down to brush against Stiles’ cheek. From the way Derek’s breathing was slowing, Stiles realized he must have finished and he relaxed a little. Derek lowered himself down carefully, his body burning with heat and slick with sweat and for a while they were both quiet, catching their breaths.

"Roll with me," Derek said after a long moment, his voice hoarse, and he hooked an arm under Stiles' chest, carefully turning them so they were on their sides. _This should be weird_ , Stiles thought dazedly, breathing in deeply. He should, by all rights, be freaking out; he had a complete stranger's dick stuck in his ass. He felt weirdly content, though, waves of pleasure still lapping over him.

Derek’s fingers caressed Stiles’ hipbone before slipping lower, trailing through the come on Stiles’ stomach. Stiles shuddered, still sensitive and a little over-stimulated from his orgasm. Derek lifted his hand, wet with Stiles’ come, and Stiles watched, a little startled, as Derek brought his hand to Stiles’ mouth. Stiles wouldn’t have, normally, but right now he was feeling punch-drunk and obliging, so he opened his mouth and sucked his come off Derek’s fingers.

Derek groaned quietly and Stiles bit back a noise because he could _feel_ Derek’s dick pulse and god, fuck, he’d discovered so many new kinks this evening. Derek exhaled against his neck, tensing slightly when he asked, “Was this…okay?”

Stiles almost laughed because Derek had gone from fucking him into the mattress to _shy._ He didn't laugh, though, settling back against Derek's chest, folding his arm over Derek's. "Way more than okay," he confirmed. Derek sighed softly, sounding a little relieved, and seemed to relax, their bodies molding to each other's shapes. Maybe it was just the post-orgasmic haze talking, but Stiles was prepared to swear he'd never felt so comfortable lying in bed with someone. He fell asleep with Derek curled around him, nosing gently at Stiles' neck. He felt safe.

-

Stiles woke some time later as the bed dipped behind him and Derek's warmth, momentarily missing, returned to his side. The room was dark, the curtains closed so he could no longer see the moon — Derek's doing, Stiles realized drowsily. He shifted sleepily and made a disgusted face; he could feel the stiffness in his muscles, the stickiness between his thighs. Derek must have slipped out of him a while ago because there was dried come there too, itchy and flaking. He looked over his shoulder to see Derek sitting up next to him, watching Stiles silently. "Hey."

Derek made a noise that could possibly be interpreted as a greeting and pushed at Stiles' side. "On your stomach," he said, and Stiles felt a moment of deja vu.

"Round two?" he asked.

Derek tilted his head to one side. "Do you want to?"

"Always," Stiles said immediately, then amended regretfully, "but I don't think my ass would appreciate it."

"I won't, then," Derek said with a slight shrug. Still, he nudged at Stiles' side until he got the hint and rolled onto his stomach, sighing into the pillow. Derek leaned forward and Stiles jumped at the cool touch of a damp washcloth on his skin. Derek carefully cleaned the mess from between his legs, then tapped him on the ass. "Flip over." Stiles turned onto his back and watched Derek clean his stomach. There was just enough light in the room for him to make out Derek's features, sharp with shadows, pale eyes hidden beneath long lashes. Stiles wanted to ask him a million questions — what rank of werewolf was he, how long did his heat last, how often did he get it, could he get Derek’s number — but he kept his mouth shut. Right now wasn't a moment to ruin with chatter.

Derek set the cloth aside but kept his hand on Stiles' stomach, touch light. He met Stiles' eyes, face smooth, expression neutral. Stiles swallowed at the intensity in his gaze, holding his breath as Derek leaned forward, pressing their mouths together. He tasted like toothpaste — either he'd had the foresight to bring his own, or there'd been some in the bathroom. It was their first kiss, Stiles realized, the first time all night that they'd been face to face. He was glad for the connection, the ability to see Derek's face and react to him.

Stiles made a quiet noise, lifting his arms to fold around Derek's shoulders, one of his hands settling at the back of his neck. There was no rush in the way Derek moved, no hurry to get off this round. He shifted without breaking the kiss, swinging a leg over Stiles' hip and settling down on top of him. Stiles liked the weight of him, heavy but not crushing. Comforting, in a way, like a security blanket.

Derek tilted his head, pressing his nose to the underside of Stiles' jaw, inhaling deeply. "I like how you smell," he admitted quietly.

"Thanks," Stiles murmured, tilting his head back to give Derek better access. He sighed softly, fingers tangling in Derek's soft hair as Derek coaxed a bruise into existence under the hinge of Stiles' jaw, then made his way down his neck. Heat began to build inside Stiles once more, quiet noises slipping from his lips. Derek lifted his head to look at Stiles, his eyes heavy and dark in the quiet of the room. Stiles could feel how hard Derek was already, a frisson running through him every time Derek's cock brushed against his.

Derek seemed in no rush, though, when he asked, "Can I blow you?"

Stiles blinked. "You, uh — yeah. Yeah, definitely."

"I want to," Derek told him. "I want to know if you taste as good as you smell."

Stiles stared at him, his cheeks flushing. "I — go ahead?"

Derek smiled faintly, his white teeth gleaming in the gloom of the room as he slid backward, pulling the sheets with him. He settled between Stiles' legs, rubbing his stubbly cheek against the inside of Stiles' thigh, giving Stiles’ cock a few lazy tugs. Stiles didn't need much encouragement; his dick was totally on board, thickening fast in Derek's grip. Derek’s eyes settled half-shut as he leaned forward, dragging his lips up the length of Stiles’ shaft before his lips parted and his tongue came out, slipping slowly across the head of Stiles’ cock. Stiles hissed, twisting his fingers in the sheets as Derek took him in his mouth, his head bobbing up and down torturously slow.

It was so different from earlier that night. Derek’s body was still hot to the touch — Stiles knew the heat couldn’t have faded that fast, unless he’d already been at the tail end of it — but his movements were so delicate now, slow and unhurried, completely devoid of the frenetic animal energy he’d had when he was digging his claws into the headboard. Stiles’ dick pulsed at the memory and Derek growled quietly, his tongue dragging across the slit to catch the precome beading there.

Stiles reached out hesitantly, then more boldly when Derek didn’t move away, trailing his hands over Derek’s cheeks and along his jaw. Derek lifted his head for a moment, nosing into Stiles’ palm before sinking his mouth back onto Stiles’ cock. Stiles breathed quietly, lips parted as he watched Derek, his lashes dark against his hollowed cheeks. He threaded his hands through Derek’s hair — surprisingly soft — and Derek made a low noise of approval, the sound vibrating up Stiles’ spine, making his breath hitch. Derek looked up at Stiles, dragging his tongue over the head of Stiles’ dick, and Stiles shuddered at the way Derek’s eyes flared red.

Fuck, somehow he’d landed himself an _alpha._ The bite on the back of his neck throbbed, reminding him that Derek could have turned him if he’d bitten deep enough — only alphas had the power to make new betas. But he couldn’t even bring himself to worry about it in that moment because Derek hadn’t broken eye contact with him, the corners of his mouth curving up as he took Stiles back into his mouth, swallowing him down so deep Stiles felt himself hit the back of Derek’s throat.

“Oh my god,” Stiles murmured, his hips trying to jolt upwards under Derek’s heavy arm. “Oh my _god.”_ He could feel himself getting close, golden heat fuzzing his brain and pooling in his groin. He was so fucking deep in Derek’s mouth he could see the bulge of his cock in Derek’s _throat,_ and Derek was so fucking gorgeous, his eyes burning crimson in the darkness of the room, his chin slick with spit and precome. “Fuck,” he groaned. “I’m — ”

Derek lifted his head, pulling off him with a slick noise, and Stiles whined at the loss, Derek holding him down as Stiles tried to follow his mouth with his hips. “You want to come?” Derek asked him, his voice dropping low. “You have to work.”

“Fucker,” Stiles muttered, avoiding his scarlet gaze.

Derek snorted, giving Stiles’ dick a few rough strokes before getting his mouth back on it. He moved slower than before, drawing out every movement — to Stiles’ frustration. He brought Stiles to the edge twice more and Stiles was swearing with every breath by the time he found release, sweat building along his spine and the bend of his knees. Derek looked up at him, a satisfied smile curving the corners of his mouth and that was it — Stiles came with a rough cry, his spine arching as come splattered across his stomach and Derek’s cheek.

_“F_ — _fuck,”_ Stiles breathed, his chest rising and falling rapidly as he tried to get his breath back. Derek watched him patiently, licking his lips clean of Stiles’ come. “Oh man,” Stiles said, flushing. “I got some in your hair, dude, sorry — ”

“Don’t worry about it,” Derek said, rising up and settling onto his knees. He swiped his thumb across his cheek and licked it clean, his eyes never leaving Stiles’ face. “Told you I like how you smell.”

Stiles swallowed, his eyes dropping to Derek’s dick, flushed and leaking against his thigh, before darting back up to Derek’s face. “And do I taste as good as I smell?”

“Mm,” Derek said, his eyelids lowering. “Even better.” He leaned forward, one hand on Stiles’ knee, the other wrapped around his own cock. Derek jerked himself off slowly, shaking his head when Stiles reached out to help. He sighed softly when he came, pushing his hand through the mess on Stiles’ stomach with a satisfied noise.

“You’re, uh, into that, huh?” Stiles said sleepily, watching Derek lick his hand clean.

“Mm,” Derek said ambiguously, sinking down on top of Stiles. Derek kissed him lazily, teeth nipping at his lips, and Stiles could taste them both, heavy and bitter on Derek’s tongue.

Stiles wanted to say something to him, something about how he’d never felt so comfortable with someone he’d just met, maybe, or something about how that had been maybe the best sex he’d ever had — but he thought about his tendency to be impulsive. Better sleep on it, he thought — probably wisely — and instead murmured sleepily, "Thanks."

"You're welcome," Derek replied quietly, dragging his nose against Stiles’ cheek, breathing softly.

As he drifted back to sleep, Stiles wondered who Derek was when he wasn't fucking strangers on full moons — where he lived, what he did for work. He wondered why Derek was even here. He was, objectively, one of the hottest people Stiles had ever seen; surely he didn't need to resort to Craigslist to find an easy fuck. He wasn’t young enough for this to be his first heat, but maybe he’d recently got out of a relationship and needed someone quick. Stiles wasn't complaining, though; for all that the night had started off confusing, he was pleased with where they'd ended up.

-

When Stiles woke for the second time, the room was soft with early morning light and he was alone. Stiles' heart sank as he realized Derek was gone — the space beside him cold, the bathroom dark and empty. Stiles sat up slowly, running a hand through his hair. A touch of that golden haze still clung to his bones, but it dissipated quickly with the realization that he hadn't even been able to ask Derek any questions — and Derek hadn't left any kind of note. He wouldn't have, Stiles supposed unhappily, pushing the sheets back. It was just a hookup.

Stiles winced as he got to his feet, legs and ass aching in protest when he straightened and tottered toward the bathroom, flicking on the light. He paused when he caught sight of himself in the mirror, his breath catching in his throat. Bruises ringed his throat, dotted his collarbones and chest. If he twisted, he could see more on the back of his neck and shoulders, including a particularly vivid one in the shape of a perfect bite mark where his neck met his shoulder. He ran his fingers over it, wincing slightly at the brief flare of pain. Derek had left claw marks on his hips and stomach, needle-thin lines not deep enough to bleed but deep enough to mark. He rang his fingers over them as well, feeling their raised edges, a shudder running through him as he remembered how they'd gotten there, Derek's heavy weight on his back, the sound of his claws scoring the headboard. His dick gave an interested twitch against his leg and he glared down at it.

"Don't even," he hissed, turning away from the mirror and stepping into the shower. It was a useless battle, though; every mark he touched sent pain and pleasure shooting through his body, head flooding with the memories of last night. Stiles sighed very softly when he wrapped a hand around himself and it was almost embarrassing, really, how little it took to get him off. He only had to think about Derek fucking into him, about how good it had felt to be pressed down into the mattress, the way it felt when Derek knotted him, and he came messily over his knuckles.

There was a cold, heavy feeling in his chest as he pulled the previous day’s clothes back on. It'd been so long since he'd hooked up with anyone that he'd forgotten why he'd stopped. It'd been good for a time, when he'd first started college, when he'd still been trying to figure out who he was and what he wanted, but after a while they'd started feeling empty. He hated waking up to an empty space next to him almost as much as he hated waking up next to an almost stranger, and what made it worse was how _good_ he'd felt last night. He kept thinking about the way his body had fit against Derek's and it made his heart sink further. He wished he'd said something. He wished he'd at least asked Derek for his number.

Stiles left the key to the room on the nightstand and drove home in silence. The apartment was empty when he got in and he was glad for it; he needed more time to process the previous night before he could stand Erica's questions. He crawled into bed because it was only eight in the morning and he'd had a long night, and slept right through the ten o'clock lab for his Supernatural Pharmacology class. When he finally dragged himself out of his room sometime around noon, Erica was sitting in the living room watching _Judge Judy._ She gave him a very judging look and said, "You look like shit."

"Thanks a lot," Stiles mumbled, staggering into the kitchen to brew some coffee. Fuck, his ass hurt worse than before, so while the coffee was brewing he rifled through the cupboards until he scrounged up a bottle of Advil.

"I don't see any bite marks," Erica said from the doorway. She added wickedly, "Not from a vampire, anyway."

"Fuck off," Stiles muttered.

"Hey," Erica said, her voice softer. "Are you okay?"

Stiles sighed. He might as well be upfront about it because Erica was going to get it out of him sooner or later. "There was no vampire," he told her. "I got the wrong room. There was a werewolf in heat and we had some really great sex and now..." He trailed off with a shrug.

"You're crashing?" Erica offered.

"I'm crashing," he agreed, scrubbing a hand over his face.

Erica stepped forward and gave him a one-armed hug — unusual for her, but not unwelcome. "What are you going to do?"

Stiles sighed again. "Well, I've got a paper to write."

Erica made an impatient noise. "No, I meant about this werewolf. A dude?" Stiles nodded slowly and she said. "Well? Are you going to try to find him again?

Stiles stared at her. "I — no? It was just a hookup, Erica. If he wanted to do it again, he would have stuck around or at least left me his number." He shrugged again, glum. "He probably woke up and realized that I wasn't the person who was supposed to be there and — well, waking up alone sends a pretty clear message, don't you think?"

"Maybe he freaked out," Erica said fairly. "Maybe it was his first time doing the Craigslist thing too."

Stiles shrugged, pouring coffee into a thermos. "Whatever. I'm going to go to school."

"Okay," Erica hollered after him, "but if you're not going to be proactive then don't expect any more sympathy from me!"

"Noted!" he yelled back, pulling on a hoodie and snatching up his bag as he headed out the door.

Stiles spent the afternoon in the library, way in the back where the back issues of all the academic journals were kept so he didn't run the chance of meeting anyone he knew. Even with his hood up, he knew the bruises around his neck were obvious and he also knew they didn't look right — he looked like he'd been _hurt,_ not fucked, and he didn't want to have to defend himself. He worked on class work for a while, getting everything pressing out of the way before he allowed himself to give in and switch his attention to the paper he needed to write for Dr. Fenris's class. It wasn't due for another week, but he wanted to get to it while his experience with Derek was still fresh in his head.

Werewolves had almost an entire row to themselves in the library, and Stiles walked up and down it for a few minutes, staring up at the shelves before pulling down a couple likely-looking volumes on physiology and behavior. He retreated back to his little corner of the library and spent some time flipping through one of the texts until he found the chapter on heats and mating. Most of what he read only confirmed what he'd already had a vague knowledge of; the heat werewolves experienced occurred multiple times a year — for omegas, it occurred as little as twice a year, while betas averaged five. Alphas experienced heat as frequently as once a month. Stiles couldn't contain the faint shudder that wracked his shoulders when he remembered the way Derek's eyes had flared red. Fuck, maybe Erica was right. Maybe, if he kept his eye on Craigslist, he'd be able to find Derek again.

The next section made him pause. Apparently there was this thing that happened sometimes called a heat bond, a chemical reaction in the body of the werewolf's partner that closely mimicked symptoms of heat; it dulled pain and increased pleasure, making the overall experience of being tied together more enjoyable. It didn't happen to every werewolf, and even with the werewolves that experienced it, it didn't occur every time. Stiles stared down at the page, his heart sinking. He was pretty sure — almost certain — that he'd experienced a heat bond. He remembered the golden haze that had wrapped around his body, infused his brain — he'd never felt like that during sex before; it had to have been. Swallowing unhappily, Stiles pulled out his phone and dialed Erica's number.

"What's up?" she asked, picking up almost immediately. "You okay?"

"Yeah," Stiles sighed. "Look, can I ask you something?"

"Shoot."

Stiles took a deep breath. This was way more than he ever wanted to know about Boyd and Erica's sex life, but — "Have you ever experienced a heat bond with Boyd?"

"Uh, no?" Erica replied, sounding a little confused. "I thought those were just an old wives' tale."

"They’re not," Stiles said glumly. It didn't really surprise him that Boyd didn't elicit heat bonds in Erica; according to the book in front of him, they were almost exclusively experienced by born wolves, and Boyd had been bitten.

"Oh, sweetie," Erica said sympathetically. "You got one, didn't you?"

"Think so," Stiles sighed. He wasn't sure why he was so bummed out about it; he hadn't even expected to get laid last night. He _should_ be happy that he did, and that it felt so great, but...maybe part of him had been hoping for more than that, like the chemistry between he and Derek had been, well, _not_ chemical. No wonder Derek had peaced out without a word that morning; he'd probably given Stiles one look and wondered what the hell he'd been thinking.

Still, he wished that Derek had mentioned something about it, so he could have prepared himself. He probably had, Stiles realized, in the exchange he’d had with whoever was _really_ supposed to be there last night. God, he was fucking stupid sometimes.

"You poor thing," Erica said, half laughing. "You've got a heat hangover."

Stiles had to laugh, because that was exactly how he was feeling. "Right."

"Here's what you're going to do," Erica instructed. "Go get yourself something greasy to eat, and then tonight Boyd and I will take you dancing."

Stiles choked back a laugh as a librarian passed by the stacks, giving him a dark look. "I thought Boyd hated dancing," he whispered.

"Oh, he does," Erica replied cheerfully, and Stiles could hear the wicked grin in her voice. "But he loves me, so he'll do it."

After he'd hung up, Stiles returned to his work feeling a lot better. He was already formulating the thesis for his paper in his head — why alphas experience more heats annually than betas and omegas, and its effect on the werewolf population as a whole — but really, he thought guiltily, his eyes sliding toward his laptop. Maybe he _could_ find Derek again, or maybe… He shrugged, flipping his laptop open. It wasn't like there was much scientific accuracy in a sample pool of one.

-

This werewolf’s name was Deucalion. He was older than Stiles, probably not much younger than Stiles’ dad, which wasn’t his thing at all, but this was for science and he had an English accent Stiles would privately admit he found kind of sexy. And anyway, he’d been the only werewolf Stiles had been able to find on Craigslist who was willing to admit that he usually heat-bonded with his partners. And he was an alpha, too. It was important to replicate all factors in an experiment. Not that Derek had been an experiment, but, well, if Stiles couldn’t replicate his results with Derek, he’d have to replicate them with the next best thing.

The next best thing had invited Stiles over to his apartment — which was _nice_ ; penthouse suite of the fanciest apartment building Stiles had ever been in — and now Stiles was on Deucalion’s couch getting blown by him and it was — it wasn’t _bad_ , but it was weird. With Derek, it hadn’t been like he’d gone out _looking_ for sex — though one could convincingly argue that seeking out a vampire was weird enough — but walking into a total stranger’s apartment knowing he was there to have sex had been fucking strange. It would have been even weirder, but Stiles had been sure to pregame this time, and he’d had three shots sitting in the passenger’s seat of Erica’s car — her idea — and by the time she’d dropped him off and he’d reached the top floor, he’d had a nice buzz and things didn’t seem so so weird.

(“Looks like you’ve already had some fun with someone,” Deucalion had said when Stiles took his hoodie off. The bruises were four days old now, purple turning to green, and they were mostly faded, except for the livid bite mark on the back of his neck, which still hurt to touch. “You a gaper?”

“Excuse me?” Stiles had blinked.

Deucalion had shrugged. “There are a lot of people — humans,” he explained, “who only have sex with werewolves in heat. We call them gapers because of — ”

“I get it,” Stiles had said. Because the werewolf’s knot would leave them stretched out, gaping. Classy. “I’m not one of them.”

“All right,” Deucalion had agreed. Stiles didn’t care if Deucalion believed him or not; it wasn’t like he had any plans to come back.)

The sex was good. It wasn’t great, but it wasn’t unenjoyable either. The heat bond hit Stiles just as his buzz began weakening, that familiar golden glow wrapping around his bones. Things went hazy after that and he let himself enjoy it because — why not? He fucking could, so he did, but after they’d both finished and Stiles lay with his chest pressed to the mattress, Deucalion breathing slowly on top of him, he had to admit to himself that it had been nothing like so good as it had been with Derek.

Derek — there’d been something about him that had been a little wild, a little out of control, like the heat had turned off some part of him that made him human. Deucalion, though…he was good at what he did, there was no denying that, but he was good in a way that was practiced. Stiles knew by the way he’d talked about meeting people that this was something he did all the time, and he had no trouble controlling his heat. It wasn’t interesting. It wasn’t that dangerous excitement that had gotten Stiles off four days ago.

When Deucalion’s knot shrank an hour later, Stiles wriggled out from under him and left without him ever waking up. He walked home, the October air cool and crisp on his skin. It wasn’t even midnight when he got back; Erica and Boyd were still awake, watching a movie on Comedy Central. Stiles waved at them as he came in, ignored the way Boyd’s nose wrinkled. He took a long shower, thinking the whole time. He felt empty again, but it was a different kind of emptiness from the way Derek had left him — this was simple dissatisfaction. Maybe he and Derek _had_ had more than the heat bond — he’d enjoyed lying next to Derek. So maybe they hadn’t had anything by way of a real conversation, but if Derek had been there when he woke up and asked if he wanted to go get breakfast or coffee or something, Stiles would have said yes like a shot.

Stiles thought about the blowjob Derek had given him, the careful way he’d touched Stiles’ skin, the way the room had been quiet and easy. There was something there, he was sure of it. Stiles absently ran his fingers over the bite mark on the back of his neck. He wanted _Derek_ , not a substitute. He wanted the real thing.

-

“Details, Stilinski,”Lydia said fiercely.

Stiles winced, cradling his phone between his shoulder and his ear as he stirred halfheartedly at a bowl of chocolate chip cookie dough, which he intended to eat raw. It was three days after he’d hooked up with Deucalion and a week since Derek and though he’d spent two hours that morning going through the past month’s posts in the supernatural section of Craigslist in hopes he might be able to find Derek’s original post, he’d had absolutely no luck. “No.”

_“Details,”_ Lydia repeated angrily. “Don’t make me scream.”

“You know, that’s getting old,” Stiles complained, dumping half a bag of chocolate chips into the bowl and then, upon further reflection, poured the rest of the bag in. “Banshee threatening to scream? You need something more original.”

Lydia took a deep breath and Stiles help the phone away from his ear, but all she said was, “C’mon, sweetheart, I’m _bored_ over here.”

“You don’t need to hear the details of my sex life!” Stiles protested. “You _have_ a boyfriend!”

“Yes, and he’s adorably vanilla,” Lydia sighed, which was kind of a relief to hear; Stiles didn’t need to know _anything_ about Scott’s sex life, thanks. “You tried to hire a vampire to suck your blood and ended up being knotted by a werewolf. I’m living vicariously through you. Now _talk.”_

Stiles sighed; just like Erica, he could never keep anything from Lydia for very long (“We Stilinski men have a long tradition of being intimidated by strong women,” his dad had sighed once, rubbing his fingers over his wedding ring). So, between spoonfuls of raw dough, Stiles told her the whole story, up to and including his fruitless Craigslist search from that morning. Lydia was quiet on the other end of the line; he could hear her tapping her fingernails against something.

Finally, she said, “So? What’s your plan?”

Stiles groaned halfheartedly, stretching out on the couch. “There’s nothing _to do,”_ he replied morosely.

“What, and that’s it?” Lydia retorted. “I know you better than that.”

Stiles shrugged, then remembered she couldn’t see him. “What _can_ I do?” he asked. “All I know is that his first name’s Derek, and he’s an alpha.”

“And likely a born wolf, judging by the heat bonds,” Lydia pointed out. “You should start asking around. There aren’t very many established packs in your area.”

“Yeah?” Stiles snorted. “And say what? ‘Hey, I accidentally had really wild heat sex with this dude — do you know him?’”

He could almost _hear_ Lydia roll her eyes. “I wouldn’t put it exactly like _that,”_ she said, sounding exasperated. “But yes, something along those lines.”

“No way,” Stiles replied. “There’s a hundred thousand people living in this city, Lydia, and who knows if he even lives in the city? He could have traveled here.”

“If you’re not going to be proactive about it, don’t expect any sympathy from me,” Lydia sniffed, echoing Erica’s words from earlier in the week almost exactly.

“I’m just trying to be realistic!” Stiles exclaimed. He sighed heavily. “Look, it would be awesome if I could find him again, but I’m not going to go crazy looking for him. I’ve got more important things to worry about — Fenris is on my ass. I’ve got a paper to write.”

“And instead you’ve having a cookie dough pity party on the couch,” Lydia said scornfully. “And you wonder why you got a C- on your last paper.”

“Thanks for the support,” Stiles retorted sarcastically.

“Well,” Lydia said dismissively, “I guess I should leave you to it, but let me know if you have any more freaky hookups.”

“I’m done with Craigslist,” Stiles said moodily. “Hey, uh, don’t tell Scott about this, all right?”

Lydia laughed. “Oh, sweetheart,” she said sympathetically, “there is no way I’m not telling him about this.”

“Figured as much,” Stiles mumbled.

“Stiles,” Lydia said, in the patient tone she only used on him once in a blue moon. “You deserve better than someone who left without waking you up. You’ll find someone.”

“Thanks,” Stiles said quietly. “I’ll talk to you later, alright?”

“I know you’ll do great on your paper,” Lydia said firmly.

After he’d hung up, Stiles sighed and set aside his bowl of cookie dough. He figured he had roughly half an hour before Lydia told Scott everything and Scott began bombarding him with curious texts — might as well get started on his paper.

-

Three weeks after his accidental one-night stand with Derek, Stiles’ second paper of the semester was handed back to him. He turned it over before Professor Fenris got even two steps away, groaning when he saw the C+ on his cover page. He flipped through to the back page, where Fenris had scrawled a brief note.

_Mr. Stilinski,_

_While I applaud your effort to get ‘hands on’ with your subject, as we discussed, I would encourage you not to forget that the preferences of one do not make the preferences of many, and as such, cannot be claimed as scientific fact - there is where the research of others_ will _come in handy. That is to say: your werewolf partner appears to have his own ‘kinks’ not shared by the rest of the werewolf community. Balancing academic research with your own personal experience is a delicate process you will learn in time._

“Now he tells me to go _back_ to the books,” Stiles grumbled, shoving the paper in his bag. He just can’t win.


	2. Chapter 2

Derek hated his sister.

“No you don’t,” Laura said cheerfully. She had his laptop resting on her thighs, her feet in his lap. She drummed her heels against his legs, grinning at the baleful look he gave her. Laura, being the mature, older sister she was, stuck her tongue out at him.

Derek shoved at her irritably. “Give me my computer.”

“Why?” she grinned, lifting it out of his reach. “Got something on here you don’t want me to see?”

 _“No,”_ Derek growled. “I don’t trust you with it.”

“Please,” Laura scoffed, typing away madly. “When have I ever given you a reason not to trust me?”

“That time you asked me to meet you for coffee and it turned out to be a blind date with that weirdo from your office — “

“Hey, Will’s a wood nymph, Der, they’ll all a bit weird — ”

“That time I asked you to house sit and you decided it’d be a good idea to to repaint my living room — ”

“You said yourself that the yellow looks good in the morning light,” Laura protested.

“I said it looks _okay,”_ Derek retorted, glowering. “What about the time you and Cora overloaded the circuits in the house and I ended up oversleeping and failing chemistry because I missed my final?”

 _“That_ was an honest mistake!” Laura argued. “I swear we were not conspiring against you — now you’re just fishing.”

Derek grunted, unimpressed. “Just tell me what you’re doing.”

Laura hesitated. “Okay,” she admitted. “You’re going to be pissed off, but I’m doing this for your benefit.”

Derek drew in a slow, calming breath. “What.”

“I _may_ have posted an ad for you on Craigslist,” she said, following this quickly with, “For a heat partner, you know? Derek — ”

 _“Laura!”_ Derek snarled, lunging at her, snatching the laptop out of her hands. “You don’t have any fucking right — ”

“Derek, you _need_ to do this with someone!” Laura protested. “You’re fucking unbearable during your heats! Just look at you — you’re four days from it and you’re a thousand times pissier than usual!”

Derek snarled at her, his fangs pushing forth from his gums. Laura’s eyes flared red in response but she managed to keep herself from shifting, instead kicking Derek in the stomach. He grunted, swiping furiously at her legs.

“See what I mean?” Laura panted, kicking his hand away. “Jesus, Der, just _listen_ to me, okay? I’m not saying you have to respond, I just want you to see you’re _desirable.”_

“If I wanted to spend my fucking heat with someone, I would!” Derek said furiously, vision bleeding red at the edges. “I’m not going to let you go behind my back — ”

“I didn’t put your name in the ad, I didn’t use a photo,” Laura protested. “I set up a fake email and everything.”

Derek maintained his glare, nostrils flaring angrily.

“Just _look_ at the responses,” Laura pleaded. “I’m not trying push you into anything — ”

“Hah!” Derek said scornfully.

Laura frowned at him. “Der, you need to take care of yourself. Your heats are just getting worse and if you refuse to get suppressants — ”

“Don’t _need_ them,” Derek hissed.

“Yeah, you do,” Laura said unhappily. “Mom says she’s going to step in soon if you don’t do something, and you definitely won’t like whatever her solution is.”

Derek slumped back against the couch, some of the anger draining from him. “Mom said that?”

Laura nodded, pursing her lips tensely. “She’ll probably pair you with someone from the pack. At least this way you get more options.”

Derek tilted his head back to stare up at the ceiling, suddenly exhausted. It’d been _years_ since he’d shared a heat with someone, and he didn’t think things had gotten that bad; usually he just locked himself in his apartment for a couple of days and fucked his hand until he felt raw. It wasn’t the optimal solution, certainly, but he’d had enough of the complications that came from spending his heat with other people.

“Am I really that bad?” he asked Laura uncertainly.

She bit her lip, eyes softening in sympathy. “Derek,” she said gently, “You’re an alpha male in your prime. Your body expects certain things of you, and it’s not getting them.”

Derek hunched his shoulders, his stomach twisting. “So it’s either get on suppressants or find someone to fuck?”

“It looks that way,” Laura said. “I’m really sorry.”

Derek shook his head. It wasn’t her fault he was scared of going on the suppressants; they were still a fairly new option and, as a result, volatile. He’d heard a lot of horror stories about other werewolves going on them — side effects ranged from violent mood swings to loss of heat all together. He’d even heard of a couple rare cases where the werewolf had lost the ability to shift, rendering them essentially human. A shudder racked him at the thought.

Laura put a hand on his shoulder. “Just think about it, all right?” she pressed. “Mom’s not going to do anything this month, but she might act soon if you don’t first.”

“Okay,” Derek muttered miserably.

Laura shifted closer, throwing her arms around his shoulders, leaning in to rub their cheeks together. Derek exhaled slowly at the familiar gesture, trying to force himself to relax. Laura hummed encouragingly, kissing his temple. “You’ll deal with this,” she said confidently. “You just might have to take a risk.”

-

Long after Laura left that night, Derek summed up the courage to check his email. He was aware there was an entire section of Craigslist devoted to supernatural encounters — Cora had used it before, which was why he summarily deleted all responses from women because he was _not_ going to take that chance. Still, it was kind of fascinating; Derek spent a few minutes browsing the listings, astounded by the things people sought — not that any of it was particularly shocking, but he’d never thought there were people out there who _wanted_ to be drained by a vampire or a succubus. It made him feel a little bit better; at least all he wanted was a fuck or two.

Alright, so despite his reluctance, he _was_ entertaining the idea. If the alternative was the suppressants or having his mom intervene and choose someone from the pack, well — he couldn’t think of a single person from the pack he’d want to couple with, and at least with the Craigslist hookup he’d probably never see them again.

Calmer now, feeling a little more confident, Derek browsed the slew of emails sitting in his inbox. He was kind of startled by the number; he’d found Laura’s posting while browsing, and all it had said was _Alpha werewolf looking for heat partner on upcoming full moon._ That was it, no pictures or anything, and it’d only been a couple of hours, but he had almost thirty emails sitting in his inbox. There were a bunch he deleted right away; he wasn’t interested in the people who skipped straight to dirty talk, and some of them looked like spam responses. Finally, Derek had narrowed the field down to a couple people. He sat in front of his computer, absently tapping his fingers against his thigh as he tried to figure out if it was something that he really wanted to do.

He wasn’t bad at sex. Even Kate, for all her bitterness, had never complained about him in that department. It wasn’t like he’d completely abstained from sex in the past couple of years, either, but a heat partner was different. The fact that he got heat bonds made things difficult; a lot of people weren’t interested in that kind of emotional handcuff when it came to hookups. When it came down to the bottom line, though, this option was much more appealing than the others.

Derek gritted his teeth and shot emails to all five of the men he’d narrowed the field down to, sure he’d be able to narrow the field down further with more communication, and it was true — by the next morning, he’d arranged to meet a man at a cheap hotel near the edge of town on the night of the full moon. Derek received a picture of him — he wasn’t bad looking, nothing stunning — and the man knew that Derek got heat bonds and was fine with it. They discussed boundaries — the guy didn’t like being held down, but he didn’t mind going home a little bruised and marked up, which was fine with Derek — he liked to _bite._

Laura wasn’t as smug as Derek thought she’d be when he told her he was going through with it. “I’m proud of you,” she said, with a faint sad smile. Derek shrugged; it wasn’t like he _disliked_ sex. If pressed, he could probably think of worse ways to spend his time.

As the days ticked closer to his heat, Derek let his supervisor know he’d be taking a couple days off — his heat usually lasted less than a day, but it was an exhausting process, and he liked to have at least a day after to recoup (Laura usually came over and they’d spend the day on the couch watching bad SyFy movies and eating as much junk food as they could stuff into their bodies).

When he woke up on the morning of the full moon, Derek could feel his heat rolling in, burning down his spine. Combined with the incessant tug of the moon, he was on edge, making him even more irritable than usual. He could feel the wolf pacing in his mind, ready to snap, fangs pushing at his gums, claws itching at the tips of his fingers. By the time it was time to head to the hotel, he was shivering with the effort it took to control himself. Stepping outside into the crisp October air was a blessing and a curse, cooling his fevered skin but intensifying his shuddering.

At the hotel, the woman behind the desk gave him an irritated look when he told her the reservation was under _John Smith._ “There are three reservations under that name,” she said, annoyed.

Derek growled, digging in his pocket to slap the copy of the reservation he’d printed onto the counter. The receptionist pursed her lips and checked the reservation number against the screen. “The other guest has already checked in,” she told Derek, who bit down on his lip to keep from shuddering in anticipation.

By the time Derek got his room key and took the elevator to the third floor, he was half hard, breathing heavily through his nose. He could smell other werewolves in the hotel, could hear their pleasure, and it was doing odd things in his head, the wolf snarling in defense, yet curious and eager, the heat clouding his thoughts. It confused him enough that when he finally reached his room and slid the key through the lock, he froze in the doorway at the sight of the young man sitting on the bed.

“Hi,” the young man said, his voice shaking with nerves. “I ate all the peanuts, sorry. I figured I’d need the extra energy — ” He cut himself off, eyes going wide at the sight of Derek.

Derek blinked hazily, his eyes flickering up and down the young man’s body. He didn’t look like he had in his photo, hair darker, body lankier, but then his scent hit Derek full in the face and he almost reeled, biting back a groan. “Take off your clothes,” Derek said unsteadily, stepping into the room as he unzipped his hoodie. Part of him was angry because the guy was supposed to be naked and ready already, but part of him was excited because it meant he got to watch those long, elegant fingers peel his clothes away, unwrapping himself like a gift. Derek swallowed as the guy pushed down his boxers and he got hit by another wave of his scent. Derek’s eyes fluttered closed for a minute, his nostrils flaring.

“On your knees,” he commanded roughly, and the kid did as he was told, kneeling on the bed with a nervous glance in Derek’s direction. Derek was shaking again, body tense with anticipation and the fight to control himself.

“Hey, uh, can I just ask?” the young man said as Derek knelt on the bed behind him. “What’s your name? Because John’s my dad’s name and I feel really weird about — “

“Derek,” he said shortly, mouth dry. He wasn’t even _touching_ the guy yet and his dick was already dripping with precome, the head of his cock flushed dark red. God, he was almost fucking _salivating._

“Okay,” the kid said. “Thanks.”

Derek licked his lips as he moved in close. The kid’s scent was changing, the smell of nerves being overcome by arousal. Derek grinned, predatory. That was what he wanted. Derek shrugged off a shudder when he brushed his hands against the kid’s thighs, thumbing his hipbones as the kid jolted under him, like he hadn’t expected Derek’s touch. Derek frowned down at him, a tendril of frustration unfurling inside him. “You’re not ready,” he said, almost a growl. The kid was supposed to have prepped himself before Derek arrived; Derek wasn’t sure he’d have the control or patience to do it himself, but it looked like he’d have to.

“Huh?” the kid squeaked as Derek licked his lips again. Fine. He’d do this himself. He was here, and he might as well fucking enjoy himself. The kid was still talking, but Derek shut him out, shifting forward and licking a thick line right across his ass.

Heat blazed up his spine at the taste of him, even better than his scent, _fuck._ Derek groaned, digging his teeth into the soft swell of the kid’s ass before diving back in. His mind was starting to fog, heavy waves of pleasure rolling up and down his body. This wouldn’t satisfy the heat for long, but for just a moment, Derek could indulge, fucking his tongue inside him as the kid pressed back against him, panting. The noise he made when Derek pressed a finger inside him alongside his tongue was enough to make Derek’s skin break out in goosebumps. _Fuck,_ he thought dazedly, pressing another finger inside. He owed Laura for this.

He was vaguely aware of the kid gasping out his name — _Stiles_ , he said, which was odd. Derek had thought his name was Mike or something but maybe he’d been using a fake name too. Whatever.

Derek needed to move faster, his moment to indulge passed as the heat began to sink in full force, sweat slipping down his spine. He’d brought lube just in case, and he was glad for it now, leaning over the edge of the bed to retrieve it from his jeans while the kid — _Stiles_ — made a disappointed noise behind him. He moved faster, slicking his hand with lube and fucking Stiles on his fingers, gripping his hip tightly to keep him from moving away.

“Please,” Stiles begged. “C’mon, _fuck me.”_

His plea hit Derek like an arrow, striking him in the heart, sending bolts of white-hot fire shooting through his body. It was all he needed; he shifted to his knees and got his hands on Stiles’ hips, then pushed inside him in one smooth movement. Stiles cried out underneath him, fingers fisting in the sheets as Derek began to fuck into him.

The world went a little dim after that, Derek’s eyes rolling back in his head at the feeling of Stiles clenched around him. Time seemed to slow, narrowing the moment, all of Derek’s being concentrated on the point where he and Stiles connected. Stiles was talking again, moaning _fuck you feel so good, fuck, fuck, yes, harder_ **.** Derek barely knew what he was doing when he shifted them upright so he could drive up into Stiles, fucking up into him as hard as he could, their bodies slick with sweat. Derek’s knot was starting to swell and part of him hated it, wanted to keep on fucking Stiles into eternity, but another part of him howled for release, fucking _begged_ for it.

Stiles was tight, clenching around him, too tight for his knot, and maybe Derek said something to him because something in his body loosened, his head turning. That long line of his neck was right there in front of Derek’s eyes and he didn’t even think about it before biting down on the juncture of neck and shoulder. He tasted Stiles’ fear for a moment, sharp and bitter, but he couldn’t stop, not now when he was so fucking _close._ Stiles reached back, his hand fisting in Derek’s hair; it threw him, forcing him off his rhythm for a moment before he found it again and slipped in home with one last thrust, tying them together. Derek pressed his forehead to the back of Stiles’ neck, panting harshly.

“Oh my god,” Stiles muttered. Derek could feel Stiles’ thighs trembling. “Fuck, can you — I need — ”

“Demanding,” Derek mumbled, licking at the back of Stiles’ neck as he wrapped a hand around him, rolling his hips up over and over in time with his thrusts. He liked the way Stiles squirmed, the way he tried to take control, but Derek didn’t let him. His release would be on Derek’s terms.

“Fuck,” Stiles whimpered, arching his spine. “Fuck, _fuck!”_ He shook when he came, body tensing against Derek’s grasp. Derek’s mouth dropped open at the scent of his release, so thick it was almost tangible on his tongue. Another tidal wave of heat crashed over him and he shoved Stiles down against the bed, rutting into him frantically. Control edged away from him; he was losing it, losing himself, the power of the moon beaming through the open window shifting him. He had one hand on the headboard for leverage and when he finally came, body shaking, the wood splintered under his nails. _Claws,_ he thought dimly, mouth open and panting as his hips rolled forward slowly. Stiles was frozen under him; Derek could taste his fear again. It took every bit of will to shift himself back, claws melting into dull fingers. He’d never lost control like that, during heat sex or otherwise.

Derek didn’t let himself move until he was certain he was back in control, and only then did he carefully lower his body against Stiles’, harsh breathing slowing. The heat was already easing, his head clearing a little as a bone-deep content set in. He took a moment to observe Stiles, laying flat and still under him. He smelled a little like fear and pain, which had Derek feeling guilty, but mostly he smelled satisfied, of the same contentment Derek felt.

“Roll with me,” Derek said gently, wrapping an arm around Stiles’ chest so he could turn them onto their sides. Stiles moved obligingly, settling back against Derek’s chest firmly, and something deep inside him loosened a little, relieved. He traced a hand down Stiles’ side, fingers bumping over his ribs, over the sharp jut of his hipbone. He could smell come on Stiles, still wet and pungent, and he trailed his fingers through it before bringing them to Stiles’ mouth, idly curious. Stiles opened his mouth and licked Derek’s fingers clean, startling a groan out of him.

Derek exhaled, dropping his arm to drape loosely over Stiles’ side. “Was this…okay?” he asked slowly.

“Way more than okay,” Stiles said softly, folding his arm over Derek’s. Derek sighed quietly, relieved, and curled around Stiles a little tighter as he drifted off to sleep.

-

Derek woke abruptly in the yellow-grey light of dawn and for a moment he laid still, staring up at the ceiling. His heat was gone, his skin cool, which was slightly startling — Derek didn’t think he’d ever had a heat pass as quickly as this one had. It was a little disappointing, he thought, remembering that violent first round and the softer, quieter second, skin tingling at the memory of Stiles’ fingers slowly stroking his face.

Derek turned his head slowly. Stiles lay on his side facing him, eyes shut, his long eyelashes brushing his cheeks. Derek gazed at him for a while, eyes slipping down his body to take in the bruises around his neck, the curve of his hips, the trail of hair under his navel that disappeared under the sheets. Derek’s eyes returned to Stiles’ face and the moles dotting his skin, and he frowned, his head clear now. Stiles didn’t look familiar at all. He didn’t look like the photo he’d sent Derek at all. Last night, Derek hadn’t been thinking straight; he’d just assumed it was an old picture or something, but —

Derek shifted, carefully leaning over the side of the bed to pull his phone from out of his jeans’ pocket. He flipped through emails until he found the one from Stiles — _Mike Nealand,_ his name was. Derek’s stomach twisted when his photo loaded, because unless the guy in bed next to him had undergone some pretty extreme plastic surgery, he wasn’t the right guy.

For a long moment, Derek froze, no idea what to do. Did he get angry? Did he wake Stiles up and yell at him? Did it fucking matter? Derek’s stomach twisted again. What the fuck had happened? How had he managed to fuck this up? And, more importantly, where was the guy he was _supposed_ to have fucked?

“Shit,” Derek hissed, remembering the receptionist telling him there’d been three reservations under the name John Smith. Of fucking course. He’d _had_ to use the stupidest name in existence. Whoever Stiles was in the hotel for, they must have used the same fucking name.

Derek’s eyes flitted back to Stiles, his throat tightening. God, no fucking wonder Stiles hadn’t been prepped. No wonder he’d still had his clothes on. No wonder he’d seemed so confused — but Derek had ignored it all, caught in the haze of his heat. _Fuck._ Had he — he hadn’t _forced_ Stiles, had he?

Derek’s mouth went dry. He needed to leave. He needed to get out of there before Stiles woke up and realized that Derek wasn’t the person he’d come to the hotel to see. Derek slid out of bed, swiftly pulling on his clothes, moving with all the quiet grace that he could summon. He didn’t let himself look back.

-

Once Derek was home, door shut and locked behind him, deadbolt turned so Laura wouldn’t be able to get in, he stopped, leaning against the kitchen counter to rub his hands over his face. He could smell Stiles all over him. He cautiously sniffed his hand, still heavy with the scent of their combined release, and shuddered at the echo of heat that shivered through his body. He needed to shower.

Derek felt guilty for leaving Stiles alone like that, but what was he supposed to say, honestly? What would Stiles have said when he woke up and found himself in bed with a stranger? Derek scrubbed shampoo into his hair, heaving out a sigh. It was just supposed to be heat sex, nothing more. No strings attached — but Stiles didn’t _know_ that. Who knew why Stiles was even at the hotel?

Derek thought about the blowjob, and how quiet everything had seemed. He hadn’t been so dazed by the heat then, though he still hadn’t noticed that Stiles wasn’t the person he was supposed to be seeing. Stiles should have noticed then, he was pretty sure, but he hadn’t said anything. Did that mean that he _had_ noticed and he didn’t care? Or hadn’t he noticed at all? Derek groaned quietly. God, he was so fucking stupid. It must have been his heat bond.

He could already feel the emptiness that always came after his heat hitting him, like a void inside his body, cold and hollow. Laura called them heat withdrawals; only people who experienced heat bonds seemed to get them. They sucked and the fucking things were part of the reason why Derek had stopped seeking partners for his heat. Someone had once told him that they sounded similar to sub drop in BDSM culture; Derek didn’t know anything about that, just that he hated the emptiness. He knew, too, that wherever Stiles was now, he was probably feeling it too, and for that Derek felt guiltier than ever.

Clean, Derek wandered into his bedroom, tugging on a pair of sweatpants as he checked his phone. A text from Laura: _why did you lock me out :( i can hear you in there_

Derek sighed quietly. _I have some things to think about today._

 _did last night go okay?_ Laura replied swiftly. Derek guessed she was probably still outside, sitting in her car.

 _I’ll tell you about it later,_ Derek texted back. She didn’t respond and he sighed quietly, shoulders slumping. Laura might be a pain in the ass sometimes, but she always respected him when he really, truly needed to be alone.

He ended up sprawled across the couch, moodily consuming an entire tub of butter pecan ice cream. The longer he sat there, the more he regretted leaving Stiles without saying anything. And now, of course, that he’d left, he had absolutely no way of getting back in contact with him. Derek’s stomach gave a guilty twist as he remembered the guy he was _supposed_ to have slept with — what the fuck had happened to him?

As it turned out, Derek had a very angry email from said Mike Nealand.

 _Dear fuckwad,_ it said. _Was that your idea of a fucking joke? i almost got drained by a fucking vampire!! If i ever trakc you down, I am going to KILL you._

Derek set his phone down slowly, mouth dry. A vampire. Stiles had been in the hotel to have his fucking _blood_ sucked, yet he’d let Derek fuck him without a word of protest? Talk about rolling with the punches. (It made Derek feel a little bit better, though; if Stiles had been in the hotel for such a radically different reason, he _would_ have said something if it wasn’t what he wanted, right? Unless he’d been scared of Derek. _Fuck.)_

Derek went to bed that night with nothing resolved, feeling like absolute shit. Laura’s reaction, when she came over the next evening after work, didn’t make him feel any better.

“Oh my god,” she kept saying. “Oh my _god.”_

Derek groaned. “Will you shut up?”

“Why didn’t you say anything to him?” Laura demanded.

“And say what?” Derek retorted. “What do you think he would have said to _me_?”

Laura shrugged expressively. “‘Thanks for the mindblowing sex?’” She rolled her eyes at Derek’s disgusted look. “Believe it or not, little brother, I _am_ aware of the fact that you’re sexually active.”

Derek glared at her for a moment before jerking his eyes away, glowering at the carpet. “Whatever. Is Mom satisfied with this?”

Laura stiffened. “Derek,” she said reproachfully. “This wasn’t about making Mom happy. This was about making your life a little easier. You had fun, didn’t you? No one got hurt.”

“Well,” Derek said guiltily, thinking about the ring of bruises and bite marks he’d left around Stiles’ neck.

Laura held up a hand, looking pained. “Okay, I don’t need to know anything about your kinks. No one got _seriously_ hurt, right?”

Derek shook his head and she raised her eyebrows. “Okay, then! You made it through your heat, you had fun, no one died. That’s good, right?”

“I guess,” Derek muttered. Laura slung an arm around his shoulders, pressing in tight against his side. He sighed, slowly relaxing against her as she stroked a hand over his hair. “Just feels like unfinished business,” he grumbled after a while.

“Well, you could have solved that yourself by saying something before you left, but you didn’t,” Laura pointed out. “So unless you’ve got some way to find him, you’re going to have to let it go.”

“You’re right.” Derek straightened, rolling his shoulders. She usually was. “You want to order pizza?”

-

For the next couple of weeks, Derek shoved Stiles and his heat to the back of his mind. Work got busy, anyway; they had several new specimens arriving in the lab, and Derek spent a lot of time standing barefoot in tanks with his pants rolled up to his knees, placing aquatic plants in icy-cold seawater. He missed his bi-weekly dinners with Laura several times trying to get the currents in the tank right, resulting in Laura appearing in the middle of the lab on a Tuesday around noon. Derek’s lab assistant, Danny, promptly disappeared at the sight of her; he’d once spilled a bucket of bait all over her, which Laura had _not_ been pleased about.

Derek himself wasn’t all too pleased to see his sister. At that moment, he was wrestling with Clara, who hated taking her supplements. Laura’s arrival distracted him enough that she was able to worm out of his grip, biting down on his hand with her mouthful of sharp little piranha-like teeth. Derek swore violently, jerking his hand out of the water, and she flopped away smugly, slapping her tail against the water as she went. Derek gave Laura a dour look as he wiped seawater off his face. “Can I help you?”

Laura ignored him, bending down to grin through the thick glass of the tank wall. “Clarabelle,” she cooed. “Are you being bad?” On the other side of the glass, Clara giggled, sending up a stream of bubbles.

Derek rolled his eyes. “I told you not to talk to her like that,” he said irritably, glaring down at the crescent-shaped bite mark on his hand, weeping blood. It was already beginning to heal, and good thing; if he wasn’t a werewolf, his arms would be covered in scars. Danny had to wear chainmail when it was his turn to feed them. “She’s five years old.”

Laura laughed as Clara stuck out her tongue at Derek. “Suck it up, Derbear,” she said cheerfully, straightening. “I’ve read articles that say baby talk’s good for language development.”

Derek frowned, licking the blood from the back of his hand. “Merfolk don’t have the same cognitive development humans do. And anyway, she — ”

Laura rolled her eyes, waving a hand to cut him off. “Not interested in your science lecture, baby brother. I’m here to take you to lunch.”

Derek eyed her suspiciously. “Why?”

“Why?” Laura repeated incredulously. “Because I can? And you’ve been spending too much time under the artificial sun lamps.”

Derek continued to glower, but he _was_ hungry. “Fine, but I need to change my shirt. And _you_ — “ He jabbed his finger toward Clara, who was floating near the top of the tank. “I’ll deal with you when I get back.” She giggled again and flipped around, disappearing down into the tank’s murky depths.

After Derek had struggled out of his damp shirt and found Danny, lurking behind Hákon’s tank, to tell him he’d be back later, he and Laura took a walk across the campus.

“Nice day,” Laura remarked with a wrinkle of her nose. “Too bad you smell like fish.”

“Hazard of the job,” Derek grumbled, jamming his hands in his jacket pockets. “We can’t all be actuaries.”

Laura snorted. “Der, when you were thinking about majors and Mom told you to _take a risk_ , I don’t think she meant devoting your life to an aquatic subhuman species. Though,” she added brightly, “you can act pretty subhuman yourself sometimes so — “

Derek lunged at her with a growl and she ducked away with a shriek, startling a group of fresh-faced undergrads — freshmen, probably, judging by the fact that it was already near November and they still looked relatively undrained by academic pressure. Laura snorted, shoving at him playfully. “Look at you making a fool of yourself,” she teased. “You’re never going to instill any fear in your students with that kind of reputation.”

Derek smiled grimly. “They’ve only let me have freshmen so far,” he retorted. “They’re _too_ easy to scare. It’s no fun.”

Laura cackled as they crossed the road, waving at a car that had stopped to let them cross. “I can’t wait until you’re about sixty-five and tenured and everyone knows you as that one professor who’s as asshole on the outside and a big ol’ softy on the inside. ‘Teddy Bear,’ they’ll call you.”

Derek glowered at her, elbowing her so hard she stumbled. “And what about you, huh? You’re just black through and through.”

“Evil and loving it,” Laura agreed. “Now, where do you want to eat? Panera?”

“All the sorority girls study there,” Derek said, shaking his head. “Blue Moon’s always fast.”

“The vegan place?” Laura groaned, dragging her feet even as she let Derek take the lead and guide them down the crowded street toward said cafe.

Derek gave her a humorous look over his shoulder. “You can pick next time,” he said, pushing open the door to the cafe.

Laura took one look at the menu and wrinkled her nose. “Pick me the least offensive thing here,” she said scornfully. “I’m going to go steal us a table.”

Derek snorted and let her go, content to wait in line. The workers here liked him, probably because they didn’t get a lot of werewolves in, and he always ordered at least three sandwiches (they were on the small side, all right? And their tofurkey was _good_ ). Panera smelled like too much sugar and preservatives, anyway; all he could smell here was fresh bread and vegetables. Laura would change her tune when he brought her one of their slabs of brownies.

“Hey professor,” the girl behind the counter said cheerfully. She wasn’t human, but Derek hadn’t quite figured out what she was yet — dryad, maybe, based on the faint green tinge to her skin. “The usual?”

“Double it,” Derek said dryly, jerking his head toward where Laura sat the front of the shop. “I’ve got a guest.”

The girl nodded, dark eyes sparkling. “Two brownies?”

Derek smiled faintly. “I come here too often.”

She smiled up at him. “It’ll be just a minute. $30.91, please.”

Derek paid and shuffled off down the bar, watching the guy behind the counter begin building his order. It took a while, other customers coming and going as their orders were completed before his. He was just thinking that he probably could have sat with Laura while he waited when someone said, “Derek?”

Derek looked up and froze; Stiles stood a few feet away, his cheeks flushed a ruddy red. Derek could smell him suddenly, his scent overwhelmingly strong. He remembered Stiles smelling good, and had attributed most of that to the heat, but here, now — Derek swayed, almost taking a step toward him before he remembered himself and where he was. “Um,” Stiles said uncertainly, his eyes flickering around the cafe nervously. “Hi.”

Derek didn’t say anything — he didn’t think he _could_ say anything. Even the sound of Stiles’ voice threw him back to that night, the memory of the way Stiles felt around him sending his skin buzzing. Stiles took a step closer to him, his lips parted. Derek’s eyes dropped to Stiles’ throat and he swallowed when he spotted the faint mark of his teeth still visible, peeping past the collar of his shirt. He made himself jerk his eyes away, staring desperately over the counter to where the guy making his sandwiches was still working.

“So, uh,” Stiles said slowly. Derek could see him rocking on his heels out of the corner of his eye. “Can I ask you something?”

Derek exhaled slowly. “What,” he replied in his most terse, uninviting tone.

“Do you — is it always like that with you?” Stiles asked. Derek swung his head to frown at him, not understanding, and cringed internally when he spotted Laura staring at them, face sharp with interest. He knew she was listening in. “Your heat,” Stiles clarified, his cheeks going a much darker red, his blush spreading down his throat.

Derek’s throat went tight as he swung his head away again. He’d been trying not to think about Stiles at _all,_ and to be honest, he’d done a pretty good job getting himself distracted by work. He had slipped a few times, mostly when he was jerking off, but in a few quiet moments, he’d come to terms with the fact that his heat with Stiles had been better than any he could remember. Whenever he thought about that quiet second round, Stiles’ hands so carefully touching his face, it made something inside him ache. Like he was missing something. He’d never felt that before.

But just as sure as he was that he’d never felt that before, he was sure Stiles had been confused by the heat bond. He didn’t know what Stiles wanted from him — was it a good thing? A bad thing? Derek settled for shrugging ambivalently. Stiles looked a little disappointed.

“Why didn’t you say anything?” Derek asked abruptly. He’d spent three weeks wondering.

Stiles looked a little startled. “About what?”

“You were there to see a _vampire,”_ Derek hissed through gritted teeth. “I — you didn’t _stop_ me.”

Stiles shrugged. “I don’t know. It seemed like a lot more fun than getting my blood sucked.”

Derek had no reason to be getting upset, but something about Stiles’ nonchalance about the whole matter rubbed him entirely the wrong way. Suddenly, he needed to be gone, as far away from Stiles as he could be.

“So,” Stiles was saying, completely unaware of Derek’s impeding internal meltdown. “Do you, uh, think we could do it again someti— ”

Laura appeared at Derek’s side without warning, leaning all her weight up against him as she put an arm around his waist, leaning up to press a kiss to his cheek. “What’s the holdup, babe?” she asked silkily, ignoring Stiles with every fiber of her being. Derek watched from his periphery as Stiles got exactly the wrong impression — which was Laura’s intent — his eyes going wide, cheeks darkening further, his scent souring with embarrassment. Derek couldn’t find it in himself to feel bad when Stiles jerked his head away, his entire body gone stiff and mortified.

“Almost ready,” Derek told Laura, and as if on cue, the guy behind the counter _finally_ finished their sandwiches, carefully stacking them in a paper bag, which he passed across the counter to Derek. “Thanks,” Derek said politely, and turned, Laura still at his side. His eyes flickered back to Stiles, who was staring down at his shoes now, jaw clenched tight. He didn’t say goodbye.

The moment they stepped out of the cafe, Laura uncurled her arm from around him and said, _“That_ was him?” Derek nodded dully and Laura made a disgusted face. “What a little d-bag. I should have kicked him in the balls, though judging by the way he smelled after I showed up, maybe that was just as good as.”

Derek exhaled harshly. “Just drop it,” he said. “Now he thinks I have a girlfriend. He’s not going to bother me again.”

Laura gave him a curious look. “Is that what you want?”

Derek made a frustrated noise. “I don’t _know,”_ he said explosively. “I’ve spent the last few weeks trying _not_ to think about it!”

“Okay,” Laura said patiently, taking the paper bag from his arms. She fished out a couple sandwiches and then pressed the bag back into his hands. “Now you’re being cranky, so I’m going to let you eat alone.”

 _“Laura,”_ Derek snapped, exasperated. but she just gave him a frustratingly calm smile and trotted off to wherever she’d parked her car, leaving Derek to stalk back across campus in an increasingly sour mood. At least the lab was empty — a note from Danny told him he’d gone to class and would be back the next day. Derek sighed, locking the door behind him and climbing the ladder of the big fifty-thousand gallon tank, sinking down onto the platform at the top.

The lab was actually an old barn, one of the few original buildings left from when the university was first founded, though it had been retrofitted with a lot of sophisticated technology to enable strict temperature and humidity control. It smelled like like salt water and fish and, very faintly, years of hay and horses. Derek found it oddly comforting, though Laura always complained, and most of the students who came through wrinkled their noses. It was always quiet, filled with the gentle sound of sloshing water and humming pumps and filters and, once in a very long while, the sound of merfolk song.

Derek slumped against the cool glass of the tank, closing his eyes as he tried to calm himself down. It was stupid to be angry, really - it’d just been a hookup. But for Stiles to act like he had the right to just pick and choose, like Derek had been part of some supernatural experiences buffet — get your blood sucked by a vampire, get knotted by a werewolf — that was not fucking okay with him. He exhaled furiously. There was probably some irony in him being angry for being used like that when the whole point of the night had been for Derek to find someone to fuck for his heat, but there’d been consent there. They’d laid down rules and boundaries and had an agreement, but Stiles hadn’t been part of any of that.

And sure, Derek was partially to blame — he hadn’t recognized that Stiles wasn’t the right person, but as hard as it would have been, he _would_ have stopped if Stiles had said something. He hadn’t, and that was — Werewolves were easily swayed while in heat, easy to manipulate. There were _laws_ regulating all sorts of legal consent issues revolving around werewolves in heat, and not just sex stuff, but business deals, any sort of legal agreement, things like that. Stiles had _known_ he was in the wrong place and hadn’t said anything; that was like lying by omission.

Derek sighed. After this experience, the suppressants weren’t sounding that bad.

His stomach growled and he sighed again, cracking his eyes open. Might as well eat the stupid sandwiches.

A flash of color caught his eye and Derek turned his head to find Lonnie hovering on the other side of the glass, watching him worriedly. She was one of the lab’s oldest specimens, a rescue from the Caribbean, where she’d been caught and half-starved in a fisherman’s net before being sent to California by a rescue group. As a grad student, Derek had spent a month straight in the lab nursing her back to health — beyond being malnourished and underweight, she’d been brought in with damaged gills and broken ribs. Laura said — a little jealously — that they had a special bond.

 _Upset?_ Lonnie signed at him, bony hands flashing through the water. She’d never picked up any human language, but she’d learned sign language readily, as fast as Derek himself could learn it to teach her.

 _I’m okay,_ Derek signed back. He shrugged a little. _Human relationships are difficult._

Lonnie bared her teeth in sympathy, her gills flaring. Derek sighed and pulled a sandwich out of the paper bag. _Hungry?_

Lonnie’s golden eyes widened and she shot to the top of the tank, breaking the surface of the water with a splash. Derek snorted, climbing to his feet as she folded her arms over the side of the tank. She gestured at him eagerly — all the merfolk loved human food — but Derek leaned forward first to scent her. Her faint, salty smell calmed him a little, and he laughed when she took his face in her scaly hands and bumped her cheek against his.

“Fine, fine,” he said, unwrapping the sandwich. “Here.”

Lonnie took it excitedly, shredding into the bread with her sharp teeth while Derek leaned against the side of the tank, trailing his fingers in the warm water. All the merfolk looked varying degrees of human, but Lonnie was probably the least humanoid-looking of all of them; rather than hair, she had a row of long spines that started at the peak of her scalp and ran down her back, long and elegant like a lionfish’s fronds. She was bright yellow all over, though the color was softer, closer to cream on her stomach, her ribs striped with long lines of electric blue.

Still, she looked entirely human when he prised one of her hands away from the sandwich to examine her scales, rolling her eyes — a gesture he was pretty sure she’d picked up from Laura. Derek ignored it, like he always did with Laura, carefully looking over her arm and long fingers. One of their other tropical merfolk had died a month ago of mystery illness he and Danny were still trying to diagnose, and Derek had become paranoid about checking all the merfolk, worried that the disease could have spread through the filtration system. To his relief, Lonnie’s scales were still slick and glittery and gleaming with health, not dry and dull like the deceased merman.

He spent the afternoon calming himself, wrapped up in work. Perhaps sensing his aggravation, the merfolk were very obliging, taking their vitamins and medications without fuss. Even Clara, when he came back to her, didn’t fight, patting the still-healing bite on his hand apologetically. By the time he got home, Stiles was a distant thought, and Derek was determined to keep him that way; he had more important things to worry about.

-

Derek spent his next heat alone. He had a hard time measuring whether it was better or worse than his last solo heat — it was hard to gauge anything when his mind was lost in an unending blaze of heat and frustration. His best intentions went out the window; he spent most of the day thinking about his last heat with Stiles. How good it had been. How Stiles had tasted on his tongue. How he’d smelled.

The heat passed slower with no one to share it with. He knotted his hand over and over, unsatisfied and burning up. When he finally jerked off for the last time in the middle of the morning after a day it first started, Derek flopped onto his back and stared out the open window. He had to admit to himself that, now that he’d passed a heat alone, and one with someone, he knew which he preferred. He’d been lying to himself for years, honestly. Maybe he’d give Craigslist another shot, but he’d be a lot more careful next time, make them tell him their name before any clothes came off. Set up a password, maybe.

The day after his heat, the new specimens were delivered to the lab — two mer brothers from the Baltic Sea. They were smaller than most of the species Derek had ever seen, but broad and muscular with thick dorsal ridges down their spines, and dark grey scales that faded to silver on their stomachs and throats. The way they moved reminded Derek of sharks. The brothers spoke only Swedish, and they were both absolutely enamoured with Danny. Derek could see they’d be trouble down the road, but for now he welcomed the distraction of their arrival.

Derek only went to one of the school’s cafeterias when he’d forgotten his wallet or was feeling particularly lazy, which was the case a couple days after the new mermen’s arrival. He was still cranky from his heat — he’d snapped at Danny earlier, and he’d made a girl in one of his classes cry, which normally would have been something to text Laura about, but now Derek just felt irritated _and_ guilty. He was starting to understand what Laura had meant about him becoming unbearable during his heats. He’d never noticed before, but after his heat with Stiles, Derek hadn’t felt like this. Apart from the momentary hollowness that came from the broken heat bond, he’d been fine. Now he was still itchy and irritable three days later, and he didn’t like it.

Derek loaded up his plate with a couple of cheeseburgers and a massive pile of french fries — because he deserved something disgustingly unhealthy, he told himself, and anyway, he’d had to wrestle with Clara again and that girl could _kick._ It was a good thing he kept spare clothes in his office.

He was just trying to decide if he wanted pizza too when he got a whiff of a scent so good it made his toes curl. Blinking in bewilderment, Derek twisted his head around just in time to see Stiles walk past him with a tray of food, deep in conversation with a curly-haired blonde girl. Neither Stiles nor the girl noticed Derek staring, but Derek — his body was doing something _stupid_. Just _smelling_ Stiles had loosened something in his chest, the itch under his skin gone for the first time in days only to be replaced with a different kind of itch. He _wanted_ Stiles, which was stupid.

Derek tried to tell himself this even as his feet carried him across the hall, settling down at a table behind Stiles’ back so he could stare without getting caught. Stiles, he tried to tell himself, was an asshole. Stiles had lied to him. Stiles — Stiles had felt _so good._ Derek took a large bite out of a cheeseburger, chewing unhappily. Stiles was what his body wanted, and he was _doomed._

He spent most of the meal alternating between staring at the back of Stiles’ head and glaring down at his plate like it had offended him, as well as fighting off a boner, which his body seemed determined to pop with or without his permission. Derek had to readjust himself several times, more uncomfortable with every movement. To make it worse, he kept getting tantalizing whiffs of Stiles, each one sending a thrill of want down his spine. Even the low sound of his voice got under Derek’s skin, and all Stiles was talking about was one of his classes. It was fucking ridiculous. Laura would be laughing her ass off if she was here.

Derek was halfway through his second cheeseburger when the blonde girl leaned across the table toward Stiles and hissed, “Hey, do you know the guy sitting behind you? He’s been staring at you like he wants to smash your face in.”

Derek froze with the burger halfway to his mouth, unable to look away as Stiles twisted around in his seat, eyes scanning the cafeteria until they landed on Derek. Stiles’ face went pink, then red very quickly. He twisted back around and told the girl, “I have no clue who that is,” in the most unconvincing casual tone Derek had ever heard.

“Oh my god,” the girl said gleefully. “That’s him, isn’t it? The alpha you fucked?”

Derek shoved his plate away with a clatter, standing abruptly. He didn’t need to hear this, to be reminded of what had happened. Stiles and the girl both glanced over at him at the noise and then away again.

“Shut up,” Stiles told the girl angrily as Derek stalked away.

“Hellooo,” she retorted. “I thought you wanted to bone him again. Why aren’t you chasing after him?”

“I _tried,”_ Stiles snapped, and that was the last Derek heard. He stalked back across campus and stormed into the lab, startling Danny and a group of undergrads gathered around the new tank. He slammed into the bathroom, locking the door behind him, and jerked off furiously. When he came, he came so hard he smacked his head against the wall. He swore violently.

It wasn’t until later, after Derek had calmed down and gone over to Laura’s for dinner — during which he made no mention of seeing Stiles again, though Laura eyeballed him like she knew something was up — that he wondered why it had never occurred to him that Stiles might be a student at the university. It wasn’t that big of a school, four thousand students, tops. The chance that they might run into each other again was pretty high. He might even have Stiles in class someday, _fuck._ He needed a plan. He needed to be prepared.


	3. Chapter 3

It seemed highly typical of Stiles’ life that, at just about the very moment Stiles had given up on ever seeing Derek again, he saw him again — in a fucking vegan cafe, of all places. Stiles knew who he was the instant he stepped through the cafe door and his eyes landed on him. It didn’t matter that Derek had his back to him, so all Stiles saw were his broad shoulders and his dark hair; he just _knew._ It was like Christmas had come early; this was his chance, here, right in front of his face, except he had _no_ fucking idea what to say.

What _did_ you say to the guy you’d accidentally slept with, who’d left before you woke without a word or note of goodbye? Okay, so, that was a pretty clear message right there, but Stiles was nothing if not optimistic, and he’d had three weeks to play through all the various scenarios in his head. Maybe Derek had been disgusted, sure, but _maybe_ he’d been so thrown by the whole thing that he’d just acted on instinct and left. Maybe he hadn’t known what to say either.

“It’s now or never, Stilinski,” Stiles muttered to himself, flushing slightly when a dark-haired woman at a nearby table raised her eyebrows at him. He set his jaw though and, bypassing the line to order entirely, stepped up next to Derek. “Derek?” he asked, wincing when his voice came out wobbly and nervous.

He watched Derek freeze, his head slowly turning to look at Stiles. Stiles swallowed. Derek looked even better than he remembered, all unfairly handsome with his stubble and v-neck t-shirt and leather jacket and those gorgeous, intense pale hazel eyes. Stiles swallowed again, goosebumps prickling over his skin. Jesus Christ, how long did the fucking heat bond _last?_

“Um, hi,” Stiles said uncertainly. He’d thought about this moment for weeks and now that it was here, he was floundering. Derek didn’t say anything; after a moment, he turned his eyes away, returning his attention to the kitchen. Stiles knew he was losing him, and he got a little desperate. “So, uh, can I ask you something?”

Derek exhaled irritably and Stiles almost turned tail and ran. He was pretty sure he’d been wrong; Derek hadn’t left because he didn’t know what to say, he’d left because he was angry. “What,” Derek said coldly.

“Do you — is it always like that with you?” Stiles asked, his words tumbling out before he could stop them. Derek frowned at him, clearly confused, and Stiles clarified, “Your heat.” He could feel his cheeks heating up. It wasn’t what he’d meant to ask — all he wanted was to get Derek’s number, maybe, see if he wanted to get coffee sometime. He hadn’t meant to bring up the heat, even though he’d thought about it every day since the full moon. He’d given up on Derek, sure, but that didn’t mean he hadn’t thought about him. He’d jerked off every day since then, pressing two fingers to the bite mark on his shoulder, which was still faintly visible. It twinged once in a while.

Derek just shrugged and Stiles rocked on the balls of his feets anxiously. He wanted to clarify further; it wasn’t so much Derek’s heat that he was interested in, but their compatibility. He’d had _fun._ But before he could say anything, Derek abruptly asked, “Why didn’t you say anything?”

Stiles blinked. “About what?”

“You were there to see a _vampire,”_ Derek growled. The bottom of Stiles’ stomach dropped away. How the hell did he know that? “I — you didn’t _stop_ me.”

Caught off guard by the fact that Derek knew what he’d been doing at the hotel — what he’d _really_ been there for — Stiles shrugged, floundering for an answer. “I don’t know.” Because he was an idiot, mostly. “It seemed like a lot more fun than getting my blood sucked.” He rocked on his feet again. God, he was failing at this. He didn’t know what he had expected — Derek to greet him with a smile, maybe, ask him to dinner or back to his place. Instead he got Derek looking everywhere but him. Fine. One more try and then he’d cut his losses and bail. “So do you, uh, think we could do it again someti— ”

The words died away on his lips as the dark-haired woman who’d raised her eyebrows at him appeared at Derek’s side, curling an arm around his waist. Of course. Of fucking _course._ God, no wonder Derek looked as though he was ready to slit his own throat. He had a girlfriend. Fuck, Stiles was an idiot. She was gorgeous too — he could have mistaken them for siblings if he hadn’t heard her call Derek _babe_ in that sultry tone. _Fuck_.

Stiles dropped his gaze to his shoes, face so hot with embarrassment it felt as though his skin was about to peel off. He didn’t look up again until Derek and his girlfriend had left. He’d never felt more embarrassed in his _life._ The guy behind the counter wouldn’t meet his eyes and Stiles didn’t blame him. That had been fucking mortifying.

He left the cafe in a hurry, only pausing to make sure he couldn’t see Derek anywhere on the street. He didn’t want to go home — Erica and Boyd were hanging out and Erica was scary good at reading him and Boyd would be able to smell him. Nope, he didn’t really want to be near any werewolves right now. Stiles headed for the library instead, to his safe corner way in the back where no one would bother him.

He hadn’t been thinking about things realistically. Since he’d never really expected to see Derek again, all his fanciful imaginations of their reunion had leaned toward the positive. He hadn’t been prepared for the absolute disdain on Derek’s face, or how he’d been so utterly dismissive — he’d probably been reliving the moment he’d woken to see Stiles in bed with him and the total disgust he’d felt. It couldn’t have gone worse if Derek had spit in his face. It really hurt.

Stiles hunched his shoulders, pulling out his phone and dialing Scott’s number, anxiously jiggling his leg as he listened to it ring.

 _“Dude,”_ Scott said excitedly, picking up after the third ring. “Did you know Twinkies are back? Lydia sent me a huge box.”

“I need to talk to you,” Stiles croaked, ashamed by the way his voice cracked.

“What’s wrong?” Scott asked, his voice immediately downshifting to a completely serious tone. Stiles had never appreciated him more; Scott was the fucking _best._ He was completely silent when Stiles told him his story, and when Stiles finished, he was quiet for another long beat before saying, “Do you know where he lives? I’ll come down there and beat him up.”

Stiles let out a watery laugh, rubbing at his eyes. “Dude, no, that’s not — ” He heaved a sigh. “I should have said something when I realized what was happening, and I didn’t. It’s my fault it went as far as it did.”

“Yeah, well, he didn’t have to be an asshole about it,” Scott retorted. “What are you doing this weekend?”

“Nothing,” Stiles replied. “But dude, you don’t need to come up here — ”

“I know, but I want to,” Scott said firmly. “You need a distraction.”

Stiles sighed, pressing the heel of his palm to his eye. “Thanks, man.”

-

Unfailingly true to his word, as always, Scott showed up at Stiles’ apartment on Friday evening with a bottle of whiskey for Stiles and a twelve-pack of werewolf-strength beer for himself. They passed the weekend in varying stages of drunkeness, Erica, Boyd, and their friend Isaac joining in for most of Saturday night. It was very late in the night — or possibly very early Sunday morning — when Stiles and Scott ended up out on the apartment balcony, sitting with their legs hanging between the rails.

Scott hadn’t made one mention of Derek, faithfully sticking to his job description of distraction, but Stiles found himself talking about it now, the words falling from his lips before he could even think about stopping them.

“I just wish it hadn’t been so _good,”_ he said miserably. “It really felt like we had a connection.”

“That’s the heat bond, man,” Scott said sympathetically. “I’ve heard of it lasting for _weeks_ for some people.”

Stiles shook his head “That’s not it. I told you about that other alpha. He wasn’t the same at all.”

Scott shrugged. “I don’t know, then. Some people are really sexually compatible, but not romantically.” He frowned. “I mean, is that what you were looking for?”

“I wasn’t looking for _anything,”_ Stiles sighed, pressing his face against the railing. “It’s not like I went to the hotel hoping to find a date, you know? But I wouldn’t have been against getting to know him better and obviously that’s not going to happen if he’s got a girlfriend.”

“It’s a shitty situation,” Scott said.

Stiles nodded, shutting his eyes for a moment. “Have you ever experienced a heat bond?”

“Yeah,” Scott said slowly, and Stiles looked at him in surprise. “You remember that girl I was seeing freshman year after Allison and I broke up?”

“Oh yeah.” Stiles blinked. “She was an omega, right?”

Scott nodded. “Yep. We spent a couple heats together, but I only felt the bond once. I’m not even sure which one of us it came from — probably from her, I guess, since she was a born wolf. It was awesome.” He tilted his head back, looking up at the star-studded night sky. “But I feel like what I felt wasn’t what you felt.”

“Yeah,” Stiles agreed dismally. “Maybe that’s the difference between two werewolves doing it and one werewolf and a human.” He scrubbed a hand through his hair. “He was just so… _dismissive._ I wasn’t expecting him to be angry at me.”

“Well…” Scott said slowly, like he didn’t want to offend Stiles. “You probably _should_ have said something, dude. I don’t blame him for being pissed.”

Stiles winced. “I fucked up.”

“Yeah,” Scott agreed, wrinkling his nose. “You kinda did.”

Stiles groaned, banging his head against the railing. “Fuck. Do you think I should apologize if I ever see him again?”

“It couldn’t hurt,” Scott said slowly. “But I mean, don’t be surprised if he doesn’t forgive you. You know werewolves in heat are vulnerable, right? What you did — it wasn’t exactly a nice thing to do.”

Stiles shut his mouth, his stomach twisting. If _Scott_ was scolding him about werewolf issues, then he had to have fucked up majorly. He’d been so busy thinking about _his_ experience that he’d given little thought to Derek’s side of things. Of course he hadn’t been happy to find out Stiles wasn’t who he thought he was; Stiles had pretty much tricked him. “Oh,” he said miserably.

Scott patted him on the back. “Another round of shots?”

“Yes,” Stiles sighed. “Please.”

-

Scott headed back to Sacramento on Sunday afternoon and Stiles spent the next week in quiet, unhappy reflection. In Professor Fenris’s class they moved onto the humanoids of the sidhe and Stiles listened diligently, already mentally mapping out his next paper — an easy one to find a living specimen of, seeing as Lydia was technically fey.

He thought a lot about Derek, wondering how hard it would be to track him down and apologize. Erica told him he shouldn’t bother. “If you see him again, you can say you’re sorry, but don’t go hunting him,” she said. “That’s too stalker-ish. He might take it worse.”

“You think so?” Stiles asked Boyd worriedly.

Boyd shrugged. “Werewolves like their privacy,” he told Stiles. “Erica’s right; he might feel threatened if you show up where he lives.”

Stiles sighed. Apparently it was up to chance, then.

-

Stiles didn’t usually eat at any of the school’s dining halls because they were as expensive as fuck and he didn’t have a meal plan, but he had two back-to-back classes on Mondays and Wednesdays with only half an hour in between that mean he either had to bring lunch or buy it, and he usually ended up buying because he almost always forgot to pack something. Erica usually joined him — she had the same gap between classes, and he wasn’t all that bothered to eat there on this particular day because it was Meatloaf Monday and the school’s meatloaf was fucking _delicious._ He happily loaded his plate high and followed Erica to a table, where they spent the next fifteen minutes cheerfully cutting down the character of Professor Harris, who Erica had for Herbal Studies on Tuesdays and Thursdays and Stiles had for Supernatural Pharmacology on Wednesdays and Fridays.

Stiles had his mouth full of meatloaf when Erica leaned forward and hissed, “Hey, do you know the guy sitting behind you? He’s been staring at you like he wants to smash your face in.”

“Huh?” Stiles said, his mouth full of food. He swallowed hard and swung his head around, eyes scanning the dining hall until they fell on Derek a couple tables over, a hamburger halfway to his mouth, his eyes wide and fixed on Stiles. Stiles could feel the blood rush to his face almost immediately. He swung back around, giving Erica a dirty look. “I have no clue who that is.”

If it had been Scott sitting there, he could have taken the hint immediately and shut up, but Erica did no such thing, a gleeful smile spreading across her face. “Oh my _god,”_ she said delightedly. “That’s him, isn’t it? The alpha you fucked?”

Stiles winced, knowing that Derek could hear her clear as day. Behind him came the clatter of dishes and he and Erica both turned to see Derek shove his plate away, abruptly getting to his feet. Stiles jerked his head away again, flushing harder. “Shut up,” he hissed at Erica, who grinned cattily.

“Hellooo,” she retorted. “I thought you wanted to bone him again. Why aren’t you chasing after him?”

“I _tried,”_ Stiles snapped, involuntarily glancing over his shoulder again. Derek was almost out of sight, striding angrily out of the dining hall. He felt like shit; this had been his opportunity to say he was sorry, and he’d completely fucked up. _Again._ He turned his glare on Erica. “Jesus, what is _wrong_ with you?”

Erica gave him a completely unperturbed look, flipping her hair over her shoulder. “What’s wrong with _you?”_ she shot back. “I thought you were going to try and talk to him!”

“I wasn’t mentally prepared!” Stiles nearly wailed. It’d never occurred to him that he’d see Derek at _school._ Derek didn’t seem like the type to still be in school; Stiles thought he seemed put together, probably a lawyer or rich businessman. _“God,”_ he groaned, scrubbing his hands through his hair.

“Hey, look on the bright side,” Erica said encouragingly. “He was wearing a school ID. That means he either goes to school here or he works here, so he should be pretty easy to track down if you want to find him.”

Stiles rubbed a hand across his face. “Yeah,” he sighed. “I guess you’re right.”

Despite this fact, Stiles held off nearly three days before looking Derek up in the campus directory. The student website had a search portal where you could look up anyone and see their ID picture and email address and, if declared, their major or field of study, but Stiles waffled for a few days before typing in Derek’s name. He wasn’t sure why it took him so long — part of him was wary of Boyd’s words, worried it’d feel like an invasion, but the other part of him knew that once he knew how to contact Derek, he’d _have_ to, and that scared him. Derek’s scorn had hurt so badly that day in the cafe, and even though Stiles knew he needed to apologize, he was afraid of having that level of disdain directed at him again.

Finally, though, Stiles holed himself up in his room and typed _Derek_ into the search bar, nervously gnawing on the drawstring of his hoodie as he waited for the results to appear, thumbnails loading slowly. And there was Derek, sure enough, looking surly third in on the second row of results. _Derek Hale,_ said the name under his photo, and Stiles clicked on it, holding his breath.

 _Derek Hale,_ the page said again, next to a slightly larger version of his ID photo. _Professor of Marine Biology and Cryptozoology._ _Bachelor of Science in Supernatural Studies, Cornell University, 2008. Master of Science in Marine Cryptozoology, UCSD, 2011._

 _“Fuck,”_ Stiles murmured. A fucking _professor._ A professor _in his school of study,_ no less. “Shit.” He ran a distracted hand through his hair. He couldn’t have fucked up worse — unless he’d slept with Professor Fenris instead, of course.

He stared at Derek’s photo for a long minute, insides squirming as he tried not to remember that night, Derek pounding into him, the blunt sting of his teeth on Stiles’ skin. Stiles shut his laptop with a sharp clack and poked his head into the living room, where Erica was watching _Say Yes to the Dress._

“Does the name Hale mean anything to you?” he asked her. He _knew_ he’d heard it before, but couldn’t place it.

“They’re like one of the biggest pack in the Bay Area,” Erica replied, not taking her eyes off the television.

_Oh. **Oh.**_

“Thanks,” Stiles told her, hurriedly backing into his room and wrenching his laptop open again. He googled _Hale Pack Bay Area_ and got page after page of results — the Hale pack attends charity events, the Hale pack donates to local schools, the Hale pack devastated by loss of alpha’s mate. Stiles clicked on that link and found himself staring at a picture of Derek looking inappropriately hot in a suit at a funeral, standing behind an older woman with his same dark hair and pale eyes. Derek’s girlfriend stood at his side, their hands clasped together, and Stiles immediately felt even worse when he saw that the article was three years old and fuck, _fuck,_ had he made Derek cheat on his girlfriend? He’d never stopped to wonder just _who_ Derek had been at the hotel for — Stiles had assumed it was another man, but fuck, what if he’d been there for some kinky role play with his girlfriend? Just how badly did the heat mess with werewolves?

Even as Stiles floundered his way into a guilt-induced panic attack, his eyes landed on the caption below the photo, which read _Alpha Talia Hale (right) and two of her children, Laura and Derek Hale, mourn the late_ — Stiles started to breathe again, even if it came out a little wheezy. Derek’s girlfriend was his sister? Something wasn’t adding up here. Either there was some _Game of Thrones-_ level shit going on between Derek and his sister or — oh. Stiles hunched in on himself, his stomach dropping. Or Derek had been so desperate to get away from him that his sister had pretended to be his girlfriend so Stiles would take the hint.

Stiles didn’t know which would be worse; that Derek was dating his sister or that he’d _pretended_ to be dating her just to drive Stiles away. He wasn’t — Stiles wasn’t that stubborn. All Derek needed to say was “Leave me alone,” and Stiles would have done it. He didn’t need to get so dramatic.

“You okay?”

Stiles shot upright, his heart nearly jolting from his chest. He turned to see Erica leaning against his doorway, a slightly concerned look on her face. “Fine,” he wheezed.

Erica wrinkled her nose. “You don’t look it.”

Stiles waved his hands around vaguely. “It’s fine, I promise. I’m handling it.”

Erica looked skeptical. “You sure about that?”

“Yes,” Stiles sighed, slowly keeling over backwards onto his bed.

Erica leaned over to stare at the picture on his screen. “He _is_ handsome,” she said appreciatively. “I’d jump his bones. I don’t blame you for going into stalker mode.”

Stiles groaned, reaching over and slamming his computer shut. “Look, he’s made it clear that he’s not interested in me, okay? I’m just going to find him and apologize and that’s it.”

Erica straightened with a laugh. “Sure, Stilinski,” she said sarcastically, “And my real name’s Bill Clinton.”

“Go _away,”_ Stiles moaned.

Erica laughed again, backing out into the hall. “Once you get a little taste of werewolf action, you never go back,” she called warningly. “I learned that the hard way.”

Stiles just grunted into his pillow, completely unimpressed.

-

Finding Derek was as easy as looking up the master class list and scanning it until he found D HALE, SS101, INTRO TO SUPERNATURAL STUDIES, which led him to Derek's faculty page — suspiciously devoid of any personal information, including a photo — which in turn told him that Derek's office was located in the Otho T. Williams Laboratory, and his office hours were one to four on Tuesdays and Thursdays. Finding the courage to go talk to him, however, took Stiles several days, one phone call to Scott, two to Lydia, and one horrible glittery banner handmade by Erica and Isaac that said _We Believe In You!!!_

Stiles still had glitter all over his hands when he finally forced himself to find the lab, a slightly ramshackle old building at the outer edge of the campus. It kind of looked like a barn — it even had a weathervane on the roof, though this one appeared to be a mermaid and not the more traditional rooster. Stiles swallowed, fiddling nervously with his phone until, like she _knew_ , Lydia sent him a text that said _Stop putting it off & DO IT_. This was followed by a text from Scott that said _he can’t be more of a jerk than he already was right?_ Erica sent him an emoticon of a thumbs up and Stiles had to wonder when all of his friends had begun to conspire against him. Then Isaac sent him an emoticon of an Easter Island head and rather than puzzle that one out, Stiles carefully pulled open one of the big wooden doors.

Stepping inside, Stiles' mouth dropped open at the sight before him. Massive glass tanks lined the walls of the building, filled with murky water and aquatic plants. Movement in the nearest one made Stiles' jaw drop further; a muscular merman came to the front of the tank to stare at him before flipping dismissively and disappearing back into the gloomy depths of the tank, thick with seaweed.

"Can I help you?"

Stiles jumped guiltily, turning to see a guy around his age emerge from between two tanks. "Hi," Stiles said, floundering a little. "I'm — I'm here to see Derek?"

The guy frowned at him. "Is he expecting you?"

"Er — no," Stiles admitted. "Definitely not. But his office hours — "

"Right," the guy sighed. "I forgot. Follow me." He turned on his heel, striding off down the long line of tanks. Stiles hurried after him, gaping unashamedly. Each tank held merfolk more interesting than the last; from one of the largest tanks, two nearly identical mermen stared at him, their golden eyes a stark contrast to their dark pewter skin. Across from them, a brilliant yellow mermaid with great long spines down her back followed him along the entire length of her tank, her eyes bright with interest. Fenris had been right, he thought guiltily. Books couldn't hold a candle to the real thing. He should have come here weeks ago.

Stiles' stomach twisted when he realized that if he _had_ come earlier, he would have met Derek like a normal person, learned his name before they had sex like normal people do. Maybe they would have dated.

The back of the building was sectioned off into smaller rooms and Stiles’ guide stopped outside one of these, leaning through the doorway. The room had a large window, through which Stiles could see Derek bent over a tub with a young mermaid in it, giggling as Derek scrubbed at her tail with a cloth. Something inside of Stiles tightened when he saw the smile on Derek’s face — that soft look, combined with the way Stiles could see his forearms flexing where he’d rolled his sleeves past his elbows, made his skin itch with want.

“Hey, Derek,” the guy said lightly. “You got a minute? One of your students is here to see you.”

Derek looked up, the smile on his face disappearing when he spotted Stiles. He said something to the guy that Stiles didn’t quite catch, and the guy turned to Stiles and said, “He’s going to finish up here. You can wait in his office.”

“Okay,” Stiles said quietly. He could feel Derek’s eyes on him as the guy led him away, down the hallway to the very back of the building. Derek’s office was next to a tiny kitchenette, where a coffeemaker burbled.

“You want a cup?” the guy asked, nodding his head toward the machine.

“Uh, no thanks,” Stiles declined. He didn’t need to get any more jittery.

The guy nodded and gestured toward Derek’s office. “Make yourself comfortable.”

“Thanks,” Stiles muttered, slinking into the room and dropping himself into a chair opposite the desk. The guy disappeared and Stiles sat still in the silence, listening to the distant hum of machinery and the occasional splash of water. He checked his phone; one message from Scott, which asked _anything?_

 _Not yet,_ Stiles texted back. He shifted uncomfortably in the chair, trying not to fidget, his body in a state of nervousness and heightened awareness. To distract himself, he swung his head around, taking in Derek’s office — it was clean and uncluttered, lined with bookshelves. Normally, he would have gotten up and leaned in close to examine the titles and artifacts filling the shelves, but he was afraid of Derek coming in and finding him snooping. He already felt guilty enough about tracking him down. He didn’t think Derek was going to be very happy with him as it was, and Stiles didn’t want to give him even more reason to be pissed.

After what felt like hours, Stiles heard footsteps coming down the hall. He stiffened, jaw tightening as Derek appeared in the doorway. He paused there for a moment, looking down at Stiles before stepping into the room, quietly closing the door behind him. Stiles watched him cross the room and sit behind his desk, and suddenly Stiles was angry, pissed at the blank expression on Derek’s face. Instead of the apology he’d been formulating for days, Stiles asked, “How’s Laura?” He felt viciously triumphant at the surprise and guilt that flashed across Derek’s face. “I’m not an idiot; I did my research. You could have just told me to fuck off.”

Derek took a slow breath, anger clouding his features. “What are you doing here, then?” he asked bitingly.

“I came here,” Stiles said slowly, pointedly, “to apologize to you.” Just like that, the anger seeped out of him, replaced by cold guilt. He looked down at his hands, his throat tightening. “I’m sorry,” he said quietly. “I should have stopped you when you came in, but I just — I got caught up in it, I guess, and that was selfish of me. I know you were there for someone else.”

Derek was silent for a long time. When Stiles chanced a glance up at him, there was an unreadable expression on his face, some mix of surprise and something else entirely. He was completely thrown off guard when Derek eventually sighed and said, “The guy I was supposed to see was _not_ happy about the vampire.”

Stiles winced. “Fuck, I — ”

“Why the vampire?” Derek asked, interrupting him. He sounded more curious than anything. “Is that something you’ve done before?”

“No,” Stiles sighed. “I was writing a paper and Professor Fenris suggested that I get more ‘hands-on’ with my subject.”

Derek raised his eyebrows, nonplussed. “Sounds like him. How’d that turn out for you?”

Stiles flushed. “I ended up writing about werewolves,” he muttered. “I got a C+. Fenris said I mixed up fact with, you know, your individual preferences.” He winced again, bracing himself for Derek to be angry for being used as a test subject, but Derek just exhaled slowly.

“Am I right to guess,” he said, “that your vampire used the name John Smith to book his room?”

“Yeah,” Stiles said uncomfortably. “And you — ”

“Did too,” Derek sighed, absently tapping his fingers against the surface of his desk. He sighed again. “Maybe you should have said something,” he said, “but maybe I shouldn’t have used the most obvious fake name in the book.”

“The receptionist told me there were three reservations for John Smith that night,” Stiles said wryly. “If mine was a vampire and yours was a werewolf, imagine what the third might have been.”

“Probably a man whose name was _actually_ John Smith, knowing my luck,” Derek said morosely.

Stiles watched him for a long moment, chewing nervously at his bottom lip before saying, “I’m sorry for the way it happened, but I can’t pretend I didn’t enjoy myself.”

Derek sighed again. “Yeah,” he agreed quietly. “I did too.”

Stiles eyed him hopefully. “Do you think we could — ”

“No,” Derek said bluntly. Then, more gently, “I don’t think that’d be a good idea.”

“Right,” Stiles said with an uncomfortable laugh. He got to his feet slowly. “I just wanted to get coffee or something, but you’re right.” He jammed his hands in his pockets, fighting against the misery rising in his chest. He shouldn’t have expected Derek to be cool with it, just like that. “I’ll see you around, I guess. And again, I’m sorry.”

Derek didn’t say anything, his mouth thin as he watched Stiles open the office door. Stiles walked slowly down the hallway, treading quietly as he passed through the row of massive tanks, the bright yellow eyes of merfolk watching him as he went. He’d almost made it to the door when someone grabbed his arm and he nearly jumped out of his skin before he twisted around and saw that it was Derek.

“What — ” he began, only to find himself cut off as Derek surged into his space and smashed their mouths together. Stiles jerked his head back with a gasp, eyes wide. “You just said — ”

Derek growled in frustration, his eyes flashing red. “I can’t get you out of my fucking head,” he said angrily. “I was _trying_ to behave.”

“I can’t stop thinking about that night,” Stiles admitted, hands curling at his sides. “I can’t — I want — ”

Derek made a low, desperate noise deep in his throat, leaning in like he was going to kiss Stiles again — before freezing suddenly, his head whipping around. He stepped back just as the guy who’d guided Stiles to Derek’s office came out of a back room, hauling a bucket of what looked like seaweed. “You need to go,” Derek said tensely, watching the guy climb a flight of stairs to reach the top of a tank.

“Seriously?” Stiles complained. “Can’t we just — ”

Derek turned his pale eyes on Stiles, looking frustrated. “I can’t _think_ right now. You — ” He cut himself off with a growl, eyes darting around the lab.

Stiles twisted and dug through his backpack until he found a pen. “Here,” he said, catching one of Derek’s hands, spine tingling at the warm touch of Derek’s skin to his. He scrawled his number across Derek’s palm. “Call me? Or text me? Just — something,” he said, feeling stupid and desperate. Derek met his eyes for one long moment, unblinking, and then he nodded, his fingers closing around Stiles’ for the briefest second. “Okay,” Stiles said quietly. “I’ll — um. Bye, I guess.”

Derek nodded again, his eyes burning crimson around the rims of his irises. Stiles swallowed and slipped out of the lab, his heart pounding his chest. He pulled his phone out of his pocket as he trotted across campus. One message from Scott: _WELL????_

Stiles grinned. _You’re not gonna believe this._


	4. Chapter 4

Derek was having a good day. The merrow from Galway had, for the first time since her arrival in the lab six months ago, allowed him to press a stethoscope to her pregnant belly and flushed a happy pale green when he told her her baby sounded healthy. She still wouldn’t tell him who the father was — Derek suspected he was human — but she seemed happy without him around, diving down into the water before resurfacing with a snail shell, which she pressed into Derek’s hands with a shy smile.

He let Laura take him to out lunch and enjoyed it, even if it meant suffering the crowd at Panera Bread. She was in a good mood too, talking excitedly about a guy she’d gone on a date with a couple days before. Derek listened patiently, content to let her happiness wash over him. It was catching, his body vibrating with positive energy as he walked back to the lab. He had a class to teach at five, but there was plenty to take care of before then, including giving Clara her monthly bath. She was still too young to know how to keep herself clean, and her scales would build up a layer of slime if not scrubbed down once in a while.

Looking after the merfolk required wearing many hats — scientist and researcher was least amongst them sometimes; doctor, caretaker, teacher, and friend came more often. With Clara, it was more like being a father, which Derek didn’t really mind. He’d grown up taking care of a myriad number of young siblings and cousins, so watching over Clara was no big deal.

She giggled when he scooped her out of the tank, one arm supporting her slippery silvery-blue tail as he carried her down the steps and into one of the back rooms, where he’d already filled a tank with warm seawater to scrub her down in. It wasn’t an easy job — Clara was ticklish, flopping around madly as he scoured her tail. Her laughter was contagious; Derek found himself smiling, the scent of her happiness pulling tension from his body.

Despite the size of his family’s pack, Derek didn’t have much to do with it. His mom had kind of thrown up her hands at him after he’d gone for his Masters, and he spent so much time at work that he missed a lot of pack events. The merfolk were more like pack than anything these days; he was, in some ways, their alpha — their happiness was paramount.

He was halfway done, soaked down the front of his shirt from Clara’s splashing, when he heard Danny behind him, leaning into the room to say, “Hey, Derek, you got a minute? One of your students is here to see you.”

Derek looked up, his eyes moving past Danny to see who’d come to talk, and all the good cheer drained out of him at the sight of Stiles standing there in the hallway. It felt like he’d been hit in the chest with a sledgehammer. Danny raised his eyebrows at him expectantly. Derek swallowed. “Show him to my office. I’ll see him in a minute.”

Danny nodded and turned to Stiles, gesturing at him to follow as he said, “He’s going to finish up here. You can wait in his office.”

“Okay,” Derek heard Stiles say, and his skin broke out into goosebumps at the sound of Stiles’ voice. Clara tugged on his sleeve; when he looked down at her, he found her staring up at him worriedly. “Everything’s fine,” he told her steadily, and got back to work, washing down her tail. He thought about Stiles the entire time, though, his heart thudding in his chest faster than usual. What did he want? Was he going to ask Derek for sex again? Hadn’t he gotten the picture with Laura the other day?

Derek eventually finished up with Clara and carried her back to her tank, slipping her a Jolly Rancher as a reward before looking back toward his office. He needed to change his shirt as the one he was currently wearing was completely soaked through, but all his spare clothes were in his office, and he wasn’t about to strip in front of Stiles. He sighed. He’d just have to suffer through it.

Upon reaching his office, Derek realized he’d have to suffer through more than just a wet shirt. Stiles sat in one of the chairs in front of his desk, slouched there like the place was his, and something about seeing Stiles in his territory sent heat flaring up Derek’s spine. He got a lungful of Stiles’ scent as he stood there watching him and had to resist the urge to close his eyes and indulge in him. He made himself move, stepping into the room and closing the door behind him — a bad move, probably, because it meant that Stiles’ scent was going to bottle up in there, soak into his clothes, but he didn’t want to chance Danny overhearing them.

Stiles watched him sit down, his face angry. “How’s Laura?” he asked sharply, another sledgehammer blow to Derek’s chest. How the fuck did he know about Laura? “I’m not an idiot,” Stiles told Derek furiously. “You could have just told me to fuck off.”

Derek took a deep breath — a mistake, because he got another mouthful of Stiles’ scent, sweet like wheat. His whole body shuddered in anticipation. He shoved his want away, letting himself be angry at Stiles for this intrusion into his life. “What are you doing here, then?” he asked bitingly. And really, what right did he have to invade Derek’s space like this? This was his _job._

“I came here to apologize to you,” Stiles retorted icily. He slumped suddenly, all the fight going out of him. “I’m sorry,” he said, voice much softer. “I should have stopped you when you came in, but I just — I got caught up in it, I guess, and that was selfish of me. I know you were there for someone else.”

Derek tilted his head back, shutting his eyes for a moment. He tried to focus on his damp shirt and how cold it felt clinging to his body, but it was impossible to distract himself with Stiles sitting across from him. He wasn’t even doing anything but Derek’s heart still pounded in his chest, his fingers curled against his thighs to keep himself from lunging across the desk and taking what he wanted. He hadn’t expected this — that day at the cafe, Stiles had seemed so flippant, but now here he was, contrite, and Derek didn’t know what to do with him. (Well. He knew what he _wanted_ to do, but not what he _should_ do.)

Eventually, as the silence between them stretched into minutes, Derek sighed and said, “The guy I was supposed to see was _not_ happy about the vampire.”

Stiles flinched. “Fuck, I — ”

 _“Why_ the vampire?” Derek asked curiously. It was something he’d been wondering since that night. “Is that something you’ve done before?”

“No,” Stiles sighed. “I was writing a paper and Professor Fenris suggested that I get more ‘hands-on’ with my subject.”

Derek raised his eyebrows. He didn’t see Fenris all that much, apart from the mandatory monthly department meetings, but he knew the man liked his students to get involved in their subjects as deeply as possible. “Sounds like him,” he said. “How’d that turn out for you?”

Stiles’ cheeks flushed ruddy red. “I ended up writing about werewolves,” he muttered. “I got a C+. Fenris said I mixed up fact with, you know, your individual preferences.”

He tensed, clearly expecting Derek to be angry. Of all the reasons Stiles had given him thus far for being in the room that night, _I was there for research_ was the last he’d expected. It was the most unbelievable too, except Stiles’ heart hadn’t stuttered over his words; he wasn’t lying. Derek supposed he should be angry to be used as a test subject, a practical experience to be used as reference material for a fucking college paper — but he was tired of being angry, and Stiles was finally being truthful. _No one got hurt,_ Laura’s voice said, echoing through his head. Let it go.

“Am I right to guess,” he said, “that your vampire used the name John Smith to book his room?”

“Yeah,” Stiles said, shifting uncomfortably in his seat. “And you — ”

“Did too,” Derek finished quietly. He tapped his fingers against the top of his desk, thoughtful. _Let it go,_ he thought again. “Maybe you should have said something, but...maybe I shouldn’t have used the most obvious fake name in the book.”

A slightly guilty expression passed over Stiles’ face. “The receptionist told me there were three reservations for John Smith that night,” he told Derek. “If mine was a vampire and yours was a werewolf, imagine what the third might have been.”

“Probably a man whose name was _actually_ John Smith, knowing my luck,” Derek said, rubbing a hand over his eyes.

Stiles sat quietly for a long moment, chewing anxiously at his lip. Derek tried not to look at him, his stomach twisting. “I’m sorry for the way it happened,” Stiles said abruptly, “but I can’t pretend I didn’t enjoy myself.”

Derek’s stomach twisted again, his body aching at the sharp scent of Stiles’ arousal. “Yeah,” he said softly. “I did too.”

Stiles looked up at him quickly, hope blooming on his face. “Do you think we could — ”

“No,” Derek said, before he could even think about it. Stiles blinked like he’d been slapped. Derek tried to gentle his tone. “I don’t think that’d be a good idea.” It really wouldn’t, he tried to tell himself. He was a professor and Stiles was a student and even though there were no rules against professors dating students who weren’t in their classes, it’d just get messy. It already was messy. Derek needed a clean start with someone new. Someone who wasn’t Stiles.

“Right,” Stiles said, laughing nervously. “I just wanted to get coffee or something, but — you’re right.” He got to his feet; Derek watched him from his periphery, not daring to meet his eyes. All the arousal in his scent had vanished, replaced by unhappiness. _It’s for the best,_ he reminded himself. “I’ll see you around, I guess,” Stiles continued, turning toward the door. “And again, I’m sorry.”

Derek didn’t say anything — he didn’t _dare_ say anything, lifting his head to watch Stiles leave the office, digging his claws into his jeans. _There,_ he tried to tell himself. That’s the end of all your problems. Now he could try again on his next heat. Clean slate.

Trouble was, he didn’t want a clean slate. He wanted Stiles. He didn’t know anything about Stiles, but he _knew_ him. Deeply. Intimately. He knew the sounds Stiles made when he was being fucked, how his body clenched around Derek when he came, how soft his face was in the dark. He didn’t think that anything Stiles had done was done maliciously. Ignorantly, yes, but Derek could tell he was trying to learn and fix his mistakes. The fact that he’d come to apologize meant a lot, because there were a lot of people in this world who would have just ignored it, held their heads high rather than say they were sorry.

“Shit,” Derek snarled, throwing himself out of his chair and through the doorway. Stiles was almost to the front doors by the time Derek caught him, curling a hand around his arm.

“What — “ Stiles began, but Derek cut him off, pressing into his space for a wild kiss, hand tight on Stiles’ arm. Just the the brief press of their lips together before Stiles whipped his head back, bewilderment on his face, was enough to set Derek’s body on fire, need and want clawing down his spine. “You just said — “

Derek made a furious noise, frustrated claws pushing at the tips of his fingers. “I can’t get you out of my fucking head,” he said frantically. “I was _trying_ to behave.” He was, he really was — if he’d let the wolf in his head do what it wanted, Stiles wouldn’t have made it out of his office; Derek would have been inside him by now, fucking him over his desk. He shuddered at the thought.

“I can’t stop thinking about that night,” Stiles admitted, pupils blown wide. “I can’t — I want — ”

Derek whined desperately, body swaying toward Stiles. He smelled so good and he was right fucking _there_ — but then he heard a door open out back and he swung his head around, catching sight of Danny coming out of the storeroom, a bucket of algae in his hands. “You need to leave,” he told Stiles, every instinct yelling at him _no, no, don’t let him go!_ But he needed to, before he did something he regretted.

“Seriously?” Stiles complained. “Can’t we just — ”

Derek gave him a frustrated look. “I can’t _think_ right now. You — “ _Drive me crazy._ He huffed, trying to fight the way his body wanted to shift, fangs itching at his gums. He wanted to slam Stiles up against a wall, suck all the energy from his lungs.

Maybe Stiles understood; he produced a pen and caught Derek’s hand, scribbling his number across Derek’s palm. “Here,” he said breathlessly. “Call me? Or text me? Just — something.” He gazed at Derek pleadingly and Derek stared back for a long moment, biting back the urge to tug him back to his office and devour him. He managed to nod, closing his fingers around Stiles’ wrist just long enough that he could feel Stiles’ pulse, racing wildly under his touch. “Okay,” Stiles said softly. “I’ll — um. Bye, I guess.”

Derek let him go reluctantly, watching him slip out the front door. When the door had shut and Stiles’ mad heartbeat faded into the distant, Derek exhaled roughly, slumping against the nearest tank. He could feel the coolness of the glass seep through his shirt, blessed relief against the heat of his skin. He watched Danny for a while, ferrying buckets of nutrient-rich algae from the storeroom to the tanks, waiting for his body to calm. It took a while; just when he’d finally think he was ready to move, he’d remember the soft taste of Stiles’ mouth, or the heat of his skin, or he’d glance down and catch sight of the numbers written on his palm.

“You okay?” Danny asked from a few feet away, another heavy bucket hanging by his side.

Derek rubbed a hand over his face, suddenly exhausted. “Yeah.”

“Who was that?” Danny pressed. “Not one of your students.”

“No,” Derek agreed.

“Hákon said you kissed him,” Danny said slyly.

Derek glared at him. “Are you being paid to gossip with the merfolk?”

“No,” Danny said, sounding completely unconcerned. “You’re late for your class, by the way.”

Derek glanced at the time on his phone and found that he was, in fact, already eight minutes late for his five o’clock class. He swore.

“I’ll make sure everyone’s fed,” Danny told him, looking amused. “You should probably get going.”

Derek sighed and pushed himself away from the tank, heading for his office. It was probably a boon that he had a class to get to, he thought, swapping his still-damp shirt with a dry one. At least he’d be distracted enough that he’d be unable to think about Stiles. Derek paused with his shirt half buttoned, glancing down at the phone number on his hand. He bent, very carefully copying the number onto a notepad, and then finished putting on his shirt, grabbing his notes and whirling out the door.

-

The next day, instead of calling Stiles, Derek went to visit his mom. It was a Saturday, and he kept himself busy in the lab all day before driving over and dropping in for dinner. He showered before he went over, but his mom still wrinkled her nose when she hugged him. “It’s nice to see you, sweetheart,” she said, delicately rubbing her cheek against his rather than comment on his scent. “Cora’s home too.”

Cora wasn’t as polite as his mom was. “You smell like fish,” she said bluntly, bashing her hip against his. Derek growled playfully, wrestling her into a headlock. Cora shrieked, struggling to break free as their mother rolled her eyes. Their youngest brother, Max, came barrelling down the front hallway and smashed into Derek, who grunted.

“You _do_ smell like fish!” he told Derek excitedly.

“They’re _merfolk,”_ Derek said, exasperated. “You met them all, remember?”

Max stared up at him blankly for a moment before his expression cleared. “Lonnie!”

Derek sighed, letting go of Cora. “That’s right.”

Dinners at the family house were always raucous events. Derek was the second oldest of seven siblings and at any one moment, he could never be sure of how many were actually at home. Toss in a couple of visiting family members or pack, and there could quickly be ten to fifteen people at dinner. Tonight was, surprisingly, a quiet night; Laura was on a date, the twins were on the east coast for their first year of college, and Tessa, who was a sophomore in high school, was at a friend’s house for the evening.

The meal was good. Derek didn’t come home as often as he might like, and he missed his mom’s cooking and his sibling’s laughter. He missed Cora; she went to school in Sacramento, which really wasn’t all that far away, but they didn’t see each other all that often. She was about Stiles’ age, he was pretty sure, a pang of guilt wrenching at his insides as he remembered that he’d yet to text Stiles, and the pleading look on Stiles’ face.

His mom gave him a thoughtful look and, after the four of them had made a lemon tart disappear, she turned to Derek’s siblings and said, “Can you guys clean up? I think your brother wants to tell me something.”

Cora looked at Derek sharply, her eyes bright and curious. “What?”

“That’s his business,” their mother said magnanimously, getting to her feet.

Cora narrowed her eyes out of him. “You better tell me later.”

Derek just scowled at her, reluctantly following his mother out onto the back porch, where no one could listen in — literally. Years ago, the deck had been plastered in privacy wards, keeping all noise contained within its screen walls, though not blocking exterior sound from coming _in_. Someone outside could stand with their ear to the windows and not hear a word. Derek’s mom settled down into an old rocking chair that could more accurately be described as her throne, her scent so deeply set into the wood that no other wolf would ever dare sit there. Derek took the porch swing, gently pushing himself back and forth, trying to settle himself.

His mom waited for a few patient moments before prodding him gently with, “Tell me what’s on your mind, sweetheart.”

Derek sighed slowly, slouching on the swing. “Laura told you about the guy I met.”

“For your last heat?” his mom asked. “All she told me is that you found someone. She wouldn’t even tell me if they were a man or a woman.”

Derek smiled despite himself; Laura always surprised him. She was always quick to joke, quick to tease, but she understood him better than anyone else, and she was quick to protect as well. Still, that meant he had quite the story to tell. It might have been easier if Laura _had_ gossiped to their mom about him.

“Well,” he said slowly, “it’s kind of a rollercoaster.” He told her — not _everything,_ because there were things his mother, even his alpha, didn’t need to know. He told her enough, though — the Craigslist mix-up, and the various encounters with Stiles.

She was quiet for a while after he’d finished speaking, gently rocking forward and backward in her chair. She ran a hand through her hair, flecked with grey. “I’m not sure what you want from me here, Derek,” she admitted.

Derek blinked. He hadn’t really thought about it himself — mostly, it’d just felt good to get it off his chest. “I — do you think I should call him?”

She turned her pale eyes on him. “I think you need to figure out what you want first.”

“I — ” Derek exhaled, frustrated. “I don’t know if I can trust him. He lied — ”

His mom gave him a patient smile. “You’re trying to apply logic to an emotional situation,” she told him. “You can reason him away as much as you’d like, but sometimes your mind makes itself up before you even realize it.”

“Like you and Dad,” Derek said, and she nodded, smiling faintly.

“Like me and Dad,” she agreed. “Look, sweetheart, you’re young. You’ve got a lot left in life to enjoy and experience. If your mind’s set on this guy, go for it. Have fun. But figure out what it is that you want, and be clear about your expectations going into it — you’re less likely to get hurt that way.”

Derek nodded slowly; his mother made a good point. She smiled again, patting her leg, and he took the invitation, rising off the swing to settle on the floor by her feet, resting his head against her legs, a position familiar to everyone in the pack. She ran her hand through his hair and he closed his eyes, breathing in her reassuring scent.

Most people didn’t realize there was a difference between being _an_ alpha and being _the_ alpha; most considered the pack system outdated, archaic, but they didn’t realize that werewolves had an inherent need for the security of family, a network of trust that they could fall back on at any time. The position of alpha was often hereditary, but not always. The presence of multiple alpha-type werewolves in a pack meant that the position could become an elected office, an individual selected by the pack. Derek’s mother had been alpha for as long as he could remember, trusted and admired by many not just in their own pack, but much of the west coast.

They sat together for a long time, Derek’s mother rocking back and forth gently, her hand smoothing over his hair over and over. Derek was half asleep when he picked up the soft patter of feet coming down the hall.

“Mom?” came Max’s voice. “Can we come out now?”

Their mother must have gestured the okay, because there came the sound of the porch door opening and closing and then Max was scrambling onto her lap, accidentally kneeing Derek in the forehead. Derek grunted and Max mumbled, “Sorry.”

“Aren’t you a little old to be sitting in Mom’s lap?” Derek grumbled.

Max, who was ten and definitely too old to be sitting in her lap, gave Derek a smug look, settling back against their mom more comfortably. Cora sat on the floor next to Derek, looping an arm around his waist and leaning all her weight against him. It was nice, Derek thought, his eyes settling half shut as his mom resumed stroking his hair. He and Laura had both moved back home for a while to help their mom with the rest of the kids after their dad died, and there’d been a lot of evenings passed this way, everyone curled together in a great pile on the porch, grieving and healing together. Tonight, it was just about bonding, all of Derek’s worries and concerns fading under the strong connection of the pack.

When Derek went home much later, he felt calm, mind and body moving more lucidly than they had in weeks. He settled into bed and stared at the post-it note he’d written Stiles’ number on. He knew what he wanted — Stiles; that was easy enough, but what of him? There’d been something there, he was pretty sure, a connection. If it had been as simple as a hookup, neither he nor Stiles would still be pursuing each other. There was no reason to keep denying his want.

Derek slowly entered the number into his phone, then typed out a message. _Hey, it’s Derek. I want to see you again._ He read it once, twice, then hit send before he could take it back. He watched his phone nervously and then, when he didn’t hear from Stiles in the first couple of minutes, made himself get out of bed and brush his teeth in an effort to distract himself. Just as he got back into bed, his phone lit up. Derek breathed in slowly as he flicked the message open.

_Pardon my enthusiasm but THANK FUCKINGG OD YES_

Derek snorted, his entire body going lax in relief. Stiles immediately followed his first text with a second: _When?_

Derek scratched at his chin. No point in putting it off any longer, he supposed. _Tomorrow? My place. I’ll cook._

 _Give me an address and a time and I’m there,_ Stiles replied almost instantly.

Derek sent him this information, resisting the urge to tell him to just come over now. _Moderation,_ he thought, remembering his mom’s words. _Be clear about your expectations._ Derek bit his lip. He didn’t want to put a damper on things, but he knew he should make his intentions clear before they got swept up in each other again.

 _I don’t want this to be casual,_ he texted, stomach twisting with nerves. Derek expected a pause, but Stiles replied within seconds. Something in Derek’s chest loosened when he read the words on the screen.

_Me either._

-

Somehow, getting through the next day was worse than the day Derek had first met Stiles, even though at that time he’d been suffering from his heat. Today, he was restless, too big for his skin, itchy and compulsive, hyper-aware of every sound and scent that crossed his path. It was the anticipation, he was sure. During his heat, he hadn’t known what he was getting into but now...he knew Stiles, knew what being with him was like, and he _craved_ it.

It was a Sunday and he didn’t need to be at work but he went anyway on the ostensible reasoning that the merfolk needed to be fed, and in the process managed to keep himself busy there the whole day. If he was irritable and short-tempered, and maybe kicked a bucket halfway down the barn, well, there was no one there to tell on him (except the merfolk and, all right, Hákon would definitely tell Danny, but that was a problem for Monday).

He stayed at work until the last possible minute, with the result that, by the time he got home from the grocery store he was running nearly half an hour behind schedule. By this time, his irritation had grown to a great festering cloud of impatience. He chopped vegetables angrily, so vigorous that he barely noticed when he sliced his thumb open. It healed almost instantly, but in the short period of time when it was bleeding, he managed to get blood all over the carrots.

Derek was glaring down at his contaminated vegetables when there came a knock on the door and his head snapped up, the whole world narrowing to a point just beyond his front door, where Stiles stood, his heart beating quick in his chest. Derek dropped the knife, absently wiping his blood-stained hands on his jeans, feet carrying him almost unconsciously to the door.

“Hi,” Stiles said when Derek opened it, Stiles trying and failing to fight back a wide grin. Derek made a strangled noise, a little overwhelmed by the fact that Stiles was _here_. For _him._   Derek wasn’t in heat but he felt like it, his skin hot, insides twisting just from Stiles’ scent. Fuck, he smelled so _good._

“Come — come in,” he managed. Stiles’ grin widened as he stepped across the threshold and right into Derek’s space, their chests almost touching.

“C’mon, man,” Stiles breathed. “Kiss me already.”

Like a flip had been switched on inside him, Derek lunged forward, shoving Stiles back up against the door, mashing their mouths together in a frantic, hungry kiss. Stiles made a deeply satisfied noise that sent sparks skipping up Derek’s spine, heady want gnawing at his heart as Stiles folded his arms around Derek’s neck, keeping him close. Derek wasn’t going anywhere; he wanted more, more, his hands slipping down Stiles’ chest, slipping under his shirt, mind buzzing at the contact, at the way Stiles’ stomach muscles tightened at his touch.

“Jesus,” Stiles hissed, tilting his head back as Derek broke the kiss and went for his throat instead, digging his teeth into his pale, tender skin. Stiles moaned, knocking his head back against the door, back arching as Derek growled. He wanted, fuck, he _wanted_ so bad. Stiles had been in his apartment less than five minutes and he was already hard, jeans too tight. Stiles felt the same; his hands were scrambling at Derek’s shoulders, tugging at his shirt. “Off, _off,”_ he said frantically.

Derek managed to back off far enough to rip off his shirt, his breath coming quickly as he watched Stiles strip off his own, his long fingers thumbing open his jeans. Stiles met Derek’s eyes, his cheeks flushed ruddy red. “I, uh,” he swallowed desperately. “I prepped myself this time.”

Derek couldn’t stop the hungry noise he made then, swaying back toward Stiles with his hands out, greedy for the touch of his skin. Stiles sighed softly, slumping back against the door as Derek gripped at his waist, thumbs pressing into the jut of his hipbones before slipping down his thighs. Stiles’ breath hitched in surprise when Derek lifted him off his feet, hands steady under his thighs. “Strong,” Stiles mumbled, hooking his legs around Derek’s waist, hissing at the glancing touch of their dicks, sensitive even through two layers of denim. He curled a hand around the back of Derek’s neck, the other flat on his shoulder for balance, and shifted experimentally, grinding into Derek, who groaned, his eyes fluttering shut.

“Fuck,” Derek mumbled, pressing in to kiss Stiles sloppily, half-distracted by the way Stiles kept moving, his hips rolling recklessly, using the door behind him for leverage. Stiles’ jeans were slipping down his hips, bunching at the tops of his thighs to reveal his underwear and the tent of his dick pushing from his open fly. Derek could smell his arousal thick in the air, precome dampening the cotton cloth of his boxers. It was heady, intoxicating — Derek had to fight the wolf inside him, shuddering as he wrestled back the urge to pop his claws, his fangs itching at his gums. He managed to get a hand between them — sans claws — and roughly palmed at Stiles’ dick. Stiles jolted at his touch, a raw, eager noise falling from his lips.

“C’mon, c’mon,” Stiles panted, his hand curling in the hair at the base of Derek’s neck. “C’mon, please — I’ve been thinking about this for _weeks.”_

Derek growled low in his throat, red boiling at the edges of his vision, dick pulsing at Stiles’ words. The scent of Stiles’ arousal was so thick in the air he could taste it, heavy on his tongue. He sucked another bruise onto Stiles’ throat to distract himself, grinding mindlessly up against him. The door rattled with every thrust and at the back of his mind he knew they were making a lot of noise — even a human would know what was going on inside — but he didn’t care. Part of him — part of him was _proud_. He wanted the whole world to know that he and Stiles were fucking. He wanted the world to know Stiles had been claimed.

 _“Derek,”_ Stiles panted impatiently, his grip on Derek’s hair tightening. Derek growled again, jerking his head out of Stiles’ grip, dropping him to the floor. Stiles caught himself, swaying a little, his eyebrows drawing together in confusion, then his expression clearing when Derek shoved down his pants and underwear, his dick bobbing free, flushed angry red at the tip. Stiles gave a little moan at the sight of him, hurrying to free himself from his own clothing.

With both of them naked, Derek curled a hand around Stiles’ wrist, intending to lead him to the couch or his bed or wherever they made it to, but Stiles tripped over his own feet after just a few steps, bowling them both to the floor and Derek thought _Fuck it._ He rolled himself on top of Stiles and kissed the surprise off his face, kissing Stiles until he was breathless and his body arched up against Derek’s, seeking friction.

There was a heavy weight settling around Derek’s shoulders, boxing in his head with a golden fog, narrowing his focus to Stiles and only Stiles. He reached down as they kissed, pressing a finger between Stiles’ thighs and shuddering at the easy way it slid inside him. Stiles whined, the tendons in his neck cording as he tilted his head back, pressing back against Derek’s hand with his whole body. He hadn’t lied about having prepped himself; Derek’s mouth fell open as he slid a second, then a third finger inside him without any effort, breathing heavily through his mouth as if he could live on the taste of Stiles’ scent alone.

All it took was a spit-slick hand on his dick to get him inside and then he was _in,_ bending over Stiles with his eyes squeezed shut at the slick heat of him. When he opened them again, chest heaving, he found Stiles gazing up at him, mouth open and lips kiss-plump and wet, and something unreadable in his eyes that stoked the flame in Derek’s bones.

“I know what you can do,” Stiles told him, voice low and raw. “Don’t you dare hold back.”

That was all the encouragement Derek needed to start fucking into him, shallow and fast. There’d be time later for finesse and a slow build up, but for now it was all heat and quick movement, Stiles hooking his legs around Derek’s waist, his fingernails digging into Derek’s shoulder blades. He tucked his head against Derek’s neck, breath hitching with quiet moans. Derek wasn’t satisfied — he wanted Stiles _loud._ He wanted the whole fucking _building_ to hear them, so he dropped down, thrusting deeper and harder, incredibly satisfied when Stiles threw back his head, gasping, “Oh fuck, _fuck!”_

He got louder and louder the harder Derek slammed into him, clawing at Derek’s back, salty tears gathering at the corners of his eyes. Derek groaned too, edging nearer and nearer to orgasm with every thrust. He was plastered to Stiles by then, not even pulling out all the way, rutting into him madly. He could barely think, barely breathe, engulfed in the intoxicating smell of Stiles’ lust, the precome leaking from his dick smearing across their stomachs. Derek rumbled low in his throat, pleased, knowing that he’d smell of Stiles for days after this. Everyone would know, everyone —

Stiles screamed when he came, completely untouched, his body jerking up against Derek’s. The sound of him, the smell of his pleasure, pushed Derek over the edge with a groan and he — he _knotted Stiles_. His knot came without warning, not there with one thrust and then swelling up with the next, locking him inside Stiles in less than a second. It happened so fast he was still moving, tried to pull out, and Stiles yelled in pain. Derek tried to freeze but he couldn’t stop moving completely, hips rolling unceasingly.

“Shit,” Derek mumbled dazedly, hips jerking helplessly as he started to come, pulsing deep inside of Stiles. “Oh, fuck — god — I’m sorry — ”

Stiles stared at him, his eyes huge and wide with surprise, tear tracks running down his ruddy cheeks. “Are you — is that your knot?”

“Yeah,” Derek hissed, moaning as a wave of pleasure crested over him. “It’s never — ”

“You didn’t say you were in heat,” Stiles said, his chest still heaving.

“I’m not,” Derek said weakly. “I’m sorry. I — ”

“Dude, don’t apologize,” Stiles said fervently. He touched Derek’s face cautiously, long fingers gentle against his hot skin. Derek shut his eyes, leaning into Stiles touch as another wave of pleasure rushed through him. “I like your knot,” Stiles added quietly, and there was no skip to his heartbeat — no lie. “Just startled me.”

“Me too,” Derek muttered, pressing his forehead to Stiles’ collarbone, shuddering with another aftershock. He was still fucking coming, his hips shaking with the power of his orgasm. Derek was completely bewildered by what had just happened; he’d _never_ knotted anyone outside his heat before, and he’d never had an orgasm like this.

Stiles hummed softly, trailing his hands through Derek’s hair. He smelled content, satiated, and his happiness helped Derek relax. He tilted his chin eventually, catching Stiles’ soft lips in a long, languid kiss. Stiles hummed again, a deeper, satisfied noise, rubbing a soothing hand down Derek’s spine. “‘s a nice hallway you got here,” he said when they eventually pulled apart, his voice amused.

Derek snorted quietly. “Sorry,” he said. “I _was_ planning on making it to the couch, at the very least.”

“I don’t mind,” Stiles said. “That was fun.” He trailed his hand through Derek’s damp hair again. “So, hey, I don’t think we ever formally introduced ourselves.”

Derek snorted again, leaning up on one elbow so he could look down at Stiles. “It’s a little late for that, don’t you think?”

“Manners don’t cost a thing, that’s what my grandma always said,” Stiles said cheerfully, grinning up at him. He offered Derek his hand. “Stiles Stilinski.”

Derek rolled his eyes but shook Stiles’ hand nonetheless. “Derek Hale.”

Stiles grinned wider, his eyes twinkling. “I hope you didn’t have anything in the oven, dude. We’re going to be here for a while.”

“I was running behind,” Derek admitted. “Seems to have been to our benefit.” He bent his head, delicately rubbing his nose against Stiles’ temple, slick with sweat. Now he could finally indulge in him, scent him over and over. Stiles turned into his touch, looping a light hand around the back of his neck, the other hand trailing up his ribs and over his pectoral muscles, tracing absent paths over Derek’s still too-warm skin. He seemed content to lie there, heart beating steadily in his chest, scent softening as the last vestiges of his arousal faded from the air. “Am I too heavy?” he asked after a while.

Stiles wrinkled his nose. “A little.”

“Here,” Derek said, curving an arm under his back and carefully rolling them, biting back a groan at the way his knot pulled at Stiles’ rim. Some color crept back onto Stiles’ face, but he kept his mouth shut as Derek managed to get onto his back and then sit upright, Stiles settled on his lap. “Think we can make it down the hall?”

“You’re the one doing all the heavy lifting,” Stiles said, one side of his mouth lifting up in a cheeky grin. Derek flashed his eyes at him, enjoying the way it made Stiles shudder. He shuddered again when Derek managed to get his knees under them, carefully rising to his feet.

 _“Oh,”_ Stiles murmured, hiding his face against Derek’s neck. Derek understood; all the movement was pulling at his knot in a way that was really hard to ignore and Stiles — well, he didn’t think that Stiles understood what pressing his face to Derek’s throat meant to a wolf, but it certainly wasn’t helping the situation. Still, Derek managed to get them down the hall, past the kitchen and the living room, and into his room. He counted it as a blessing that he didn’t live with roommates.

“This is the weirdest house tour I’ve ever gotten,” Stiles said, his face still pressed up against Derek’s neck. Derek shuddered at the vibration of his voice, carefully lowering himself to sit at the edge of the bed before he lost control of his legs. Stiles seemed to pick up on what he was feeling, though, because his scent began to change subtly, the spicy tang of arousal seeping back into it. He tilted his head, pressing a soft kiss to the hinge of Derek’s jaw, smiling at the quiet noise Derek made. It went against the fiber of his being to tilt his head back and show his throat, but it was oh, so worth it for the wet kisses Stiles lavished on him, all soft lips and blunt drag of his teeth.

He didn’t resist when Stiles pushed at his shoulders, lowering himself to the bed, hands sliding down to Stiles’ hips. Stiles followed, leaning over him and kissing him slowly, delicately tracing his features with his long fingers. Still locked inside Stiles, Derek was beginning to get hard again, his hands tightening on Stiles’ hips so he could roll his own upward. Stiles exhaled softly, his eyes fluttering shut for a moment before he straightened, keeping one hand on Derek’s chest for balance.

Derek watched heavy-lidded as Stiles began to ride him. With Derek’s knot inside him, Stiles couldn’t lift himself, so he just rolled his hips unceasingly, grinding down on him, body tightening around Derek’s knot in a way that made him bite down on his lip to keep himself under control. He let Stiles control the pace, oddly anchored by the hand he kept on Derek’s chest. It kept him from feeling weightless and unsettled, helped him keep his control.

Stiles brought his other hand to his dick and began to jerk himself off with long, easy strokes, clearly in no rush to get himself off. Derek felt the same; there was heat licking at his bones, but it wasn’t the inferno it had been earlier. He was happy to watch Stiles jack himself off, listening to his heartbeat jump, long eyelashes fluttering as he fucked up into his hand and back down on Derek’s dick. Derek ran his hands up Stiles’ thighs, squeezed at his hips, swallowed hard when Stiles tilted his head back, exposing the pale column of his throat, mouth falling open as he came silently, adding fresh white streaks of come to the dried mess on Derek’s stomach.

Derek watched him, his stomach tightening at the way Stiles looked at him after he came down from his high, little shudders shivering up his body. There was something fierce in his gaze, possessive. Grateful. Derek was suddenly very glad he’d given this a chance.

“Come on,” Stiles murmured, leaning over Derek, bracing his hands on either side of his head. “Your turn.”

Derek groaned quietly, hands squeezing at Stiles’ hips as he fucked up a little harder, surprised when Stiles thrust back just as eagerly. It didn’t take long before he was coming too, back arching off the bed, Stiles mumbling “So good,” into his cheek. The second orgasm was nowhere near as good as the first, though still amazing, Stiles rolling his hips through it until Derek held him still.

“I think we just reset the timer,” Derek murmured as Stiles collapsed on top of him, boneless.

“‘s fine with me,” Stiles muttered, shifting around until he was comfortable. “Could take a nap.”

“Mm,” Derek agreed. His legs were hanging over the edge of the bed and his toes were numb, but his body felt heavy with satisfaction - he didn’t feel at all inclined to move again, maybe ever. Stiles must have felt the same; he yawned hugely and said, “See you on the other side,” and was asleep within moments.

Derek wasn’t far behind.

-

“What happened here?” Stiles asked, raising his eyebrows at the carrots on the chopping board, covered in suspicious red-brown splotches.

It was a couple hours after he’d arrived; they’d slept for a while, and Derek had woken to Stiles carefully pulling off of him, making a face at the mess between his thighs. If Derek had his way, they would have forgone the shower that followed, but he understood that humans didn’t have the same sensitivity to scent that werewolves did and anyway, even after the shower Stiles was soaked in his scent, and he in Stiles’. It made him a little giddy, standing in the kitchen, watching Stiles lean against the counter in a borrowed shirt and basketball shorts. He doubted Stiles had any idea how wearing Derek’s clothes affected him.

“I had an accident,” Derek admitted.

“I can see that,” Stiles replied. “It looks like a massacre.” He tapped his fingers against the counter. “How about takeout? I’ll pay.”

Derek was fine with that because it meant they could make out on the couch for the half hour it took for their pizza to arrive. By the time the doorbell rang, Derek had lost his shirt and when he opened the door, the wood nymph pizza delivery girl took a startled step backward, her nostrils flaring. Derek knew his eyes were probably burning red, and he reeked of pheromones. He smiled slowly at her as he handed over the bills Stiles had passed him, feeling deeply satisfied.

When he came back into the living room, carrying the pizza, Stiles made a noise almost as erotic as the noises he’d made earlier, reaching eagerly for the box. “I’m fucking _starving,”_ he told Derek, opening the box with a happy sigh. “That was a workout and a half.”

Derek snorted softly, dropping down onto the couch next to him and leaning over to grab a slice. Stiles slumped against his side, comfortable on the surface, though Derek could scent a little nervousness on him.

“You think this is weird?” Stiles asked after consuming three slices of pizza.

“Is what weird?” Derek asked.

“This whole thing,” Stiles said, gesturing expansively. “How we met.”

“A lot of people meet in odd ways,” Derek pointed out. He thought about it for a moment. “It _is_ weird,” he added, “but it doesn’t bother me. Does it bother you?”

Stiles shook his head, reaching for another slice of pizza. “No. It’s just a little hard to explain.”

“Did you ever hear from your vampire?” Derek asked.

Stiles shook his head again. “Not a word. You’d think he’d be pissed about it, but maybe it wasn’t worth the effort to complain, I don’t know.”

“He’s probably had people back out before,” Derek said.

Stiles made a thoughtful noise. “Was that…your first time doing the Craigslist thing?”

“Yeah,” Derek admitted quietly. “I — my sister set it up.” He hesitated before adding, “I’m sorry about that day at the cafe. I was angry, but that...was a cruel thing to do.”

Stiles shrugged. “You made your point.” He grinned wryly. “Dude, I thought you had some freaky Lannister thing going on for a moment after I found out who she was.”

Derek snorted. “We’re close, but not _that_ close.”

“Good,” Stiles said firmly. He didn’t smell nervous anymore, tilting his chin to catch Derek in a soft kiss. “You want the last piece of pizza?”

“Go for it,” Derek told him, body warm as he watched Stiles lean forward and grab the last slice. He was happy and full, sated in more ways than one.

-

Stiles spent the night.

Derek didn’t think either of them were planning on it — he certainly hadn’t been. After they’d spent a couple hours lazing on the couch together, Stiles stretched languidly and said, “I better get going.” There was no hint in his voice that he wanted an invitation to spent the night, but Derek was a little surprise to find he didn’t _want_ Stiles to leave. He liked the way Stiles fit against his side, a solid line of heat and comfort. It was easy having him there, no demands being made of him.

It cost Derek nothing at all to ask “Stay?”

Stiles looked at him, his head tilted consideringly, and said “Okay,” easy as pie.

Derek wasn’t exactly planning on having sex with him again either — or not that night, anyway — but it felt so right, so easy with Stiles tucked against the curve of his body as they lay in his bed. The room was already infused with the thick scent of their earlier round, tickling at Derek’s nose, making heat prickle up his spine. He pressed his nose to the back of Stiles’ neck, dragging his lips against his skin. He had to resist the urge to bite down and claim, though he still couldn’t help but find the place where he’d bitten Stiles that first time, at the juncture of neck and shoulder, and rest his teeth there. Stiles shuddered a little, pressing back against Derek, sighing a little.

“Can I?” Derek murmured into Stiles’ shoulder, slipping a hand under Stiles’ shirt — _his_ shirt — and flexing his fingers against Stiles’ firm stomach.

 _“God,_ yes,” Stiles replied. “Though if I can’t walk tomorrow, I expect you to carry me to class.”

Derek snorted as he slid a hand under the waistband of Stiles’ — _his_ — shorts, nose pressed to the soft stretch of skin behind Stiles’ ear, breathing in deeply as Stiles’ scent began to sweeten with arousal, his dick stiffening as Derek wrapped his fingers around it. Stiles groaned softly, bending to shove his shorts down past his knees, kicking them off the rest of the way. He groaned again when Derek  ground his hips against Stiles’ ass, reaching back to clutch at Derek’s hip.

“God,” Stiles moaned, hips jolting as Derek’s hand left his dick, a careful finger pressing at his entrance. “I’m going to get addicted to this.”

“Good,” Derek growled, reaching down to pull off his boxers. Stiles shifted around until he was half on his stomach, drawing a knee up to give Derek better access to him. Derek made an approving noise, pressing a second finger inside him easily, Stiles still slick and loose from their earlier rounds, but not quite enough for Derek to be able to push in on that alone. He lifted himself up, stretching over Stiles to reach for the nightstand drawer, pulling out a bottle of lube.  Stiles hummed approvingly when Derek pressed his fingers back inside him, now slick and cool with lube, stretching him slowly until he was ready and open for Derek.

“Ready?” Derek rumbled, aligning himself, the head of his dick brushing against Stiles’ hole.

“Ages ago,” Stiles mumbled, sighing happily when Derek pushed inside in one smooth movement, not stopping until Stiles’ ass rested flush against Derek’s hips. Derek lay still for a moment, breathing slow and warm against Stiles’ neck, his body hot and already starting to grow sweaty where he was pressed up against Stiles’ back, sweating through the thin cotton of his t-shirt. He rubbed an absent hang up and down Stiles’ side, following the dips of Stiles’ ribs in an almost comforting gesture before dropping down to scrape his nails through the trail of hair below Stiles’ bellybutton. He liked the way Stiles’ breath hitched when Derek curled his fingers around his cock again, hips jolting up and into Derek’s grip.

It was so quiet in Derek’s room, so different from their earlier scene in the hallway. Derek focused on getting Stiles off, spending a lot more time fisting Stiles’ dick, sucking bruise after darkening bruise into his neck and shoulders. He wouldn’t let Stiles pick up the pace; he'd let go of Stiles' dick and put a firm hand on his hip if Stiles tried, holding him still effortlessly. It was a different type of control than the first time they’d fucked, still exciting, and Stiles stopped trying after a while, letting Derek use his body.

Derek fucked in and out of him slowly, matching the movement of his hips to the slow tug of his hand on Stiles’ dick, so concentrated on the low noises Stiles made, that he barely noticed when he knotted Stiles again — except there was no way he could ignore how Stiles’ body tensed around around him, his head going loose and fuzzy as his own orgasm hit without warning. He pressed his forehead to the back of Stiles’ neck with a small, almost helpless noise, shaking his way through it. Stiles made a soothing sound, reaching back to squeeze at Derek’s sweaty flank, rocking his hips to carry Derek through it.

He was still coming, lost in a mindless sort of haze, when he tightened his hand around Stiles’ dick and twisted his wrist sharply. Stiles came with a sudden, startled gasp, his body curling as he tightened around Derek, who made a rough noise of satisfaction, biting down on that familiar place on Stiles’ shoulder. Stiles made a sound somewhere between a whimper and a moan, a second weak spurt of come leaking over Derek’s fingers. Derek laughed under his breath, deeply pleased.

“That’s it,” Stiles mumbled, his quick breathing beginning to slow as he came down from his orgasm. “I don’t think I’m walking tomorrow.”

Derek laughed again, body loose as he nuzzled against Stiles’ neck, dragging his fingers through the wet mess on Stiles’ stomach. “I’ll drive you,” he murmured. “If you want.”

“Thanks,” Stiles said quietly, settling himself more comfortably against Derek’s chest. “Thanks,” he said again after a while. “For giving me another chance. This whole thing is really weird but I — I’m glad it all worked out.”

“Me too,” Derek agreed quietly. He hesitated a moment before offering, “I hadn’t been with anyone for a while — for my heat, I mean. When I was with you, it was — it was fun. For the first time.”

“Seriously?” Stiles asked, not skeptical, but startled.

“Yeah,” Derek said softly. “Most people - they don’t like the complication of the heat bond.”

“That was kind of a surprise,” Stiles admitted. “I mean, it was _awesome_ when we were together, but afterward — I felt like I was hungover.”

“Laura calls it heat withdrawal,” Derek told him. “It’s easier on both partners when they can spend some time together after. I didn’t really think about it before arranging the whole hookup thing.”

“Well,” Stiles said slowly, a little hesitantly, “I can be around after the next one, if you want me to be.”

Derek breathed out slowly, sensing Stiles tense with nervous anticipation. “I’d like that,” he said slowly, and Stiles went lax in relief.

They fell silent after that, Derek slowly stroking his hand up and down Stiles’ side until, eventually, Stiles went completely limp against him, his breathing slow with sleep. Derek was awake for a while yet, face tucked against Stiles’ shoulder blades, breathing in his scent. He didn’t know what it meant that he’d knotted Stiles outside his heat — he personally only knew a couple werewolves who’d been able to do it, and as far as he could remember, there was no common thread between any of them. He’d heard rumors — werewolf lore — that mates could knot outside of heat, but they were just that: lore. There’d been a time when he was younger that he’d spent a lot of time dreaming about the day he’d find his mate, entranced by all the fairy tales his mom used to tell of wolves who’d met their match; years in academia, however, had taught him that _mate_ was just a label for a matched pair, nothing magical about it.

Still, Derek thought, the movement of his hand stilling as he slipped into sleep. Magical or not, he and Stiles had a connection, and he wasn’t going to let it go to waste.

-

Derek woke the next morning to the bed empty next to him and the smell of bacon in the air. He could hear Stiles in the kitchen, muttering something under his breath. Derek smiled to himself before heading for the bathroom, taking a quick shower, cleaning himself of yesterday’s sweat and come. The air was humid in the bathroom — Stiles had apparently showered before him. It said something, he thought, scrubbing shampoo through his hair, that Stiles could rise and move around the apartment without waking him. He might not trust Stiles completely yet, but he felt…relaxed.

Further tension seeped out of him after he got dressed and went into the kitchen, where Stiles leaned against the counter with a plate of food in his hands.

“Hey man,” Stiles said around a mouthful of scrambled eggs. He gave Derek a hesitant smile. “I hope you don’t mind me eating you out of house and home. Left some for you.”

“That’s fine,” Derek said quietly, moving over to the coffeemaker. Stiles had made coffee, too. He poured himself a cup and leaned up against the counter next to Stiles, who leaned just close enough to press their hips together. Derek sighed softly, content, and turned his head, unable to resist nuzzling at Stiles’ jaw. He’d changed back into the clothes he’d arrived in yesterday, which was disappointing — even though he fairly _reeked_ of Derek anyway. He was a little upset they didn’t have more time; he’d like to get down on his knees and let Stiles fuck his mouth, maybe rim him until his legs gave out…but that was for another time, he supposed.

Stiles hummed quietly, biting a piece of bacon in half and offering him the other half while he chewed thoughtfully. Derek shook his head. Stiles swallowed and said, “I was thinking.”

“Yeah?” Derek asked, swaying back to take a sip of coffee.

“Well, Fenris said that we could rewrite one of our papers and submit it for a better grade and I was hoping I could — ”

“Use me,” Derek finished, a deep cold settling into the pit of his stomach. He wasn’t a test subject, he wasn’t —

“No,” Stiles said hurriedly, his eyes going wide. “Not you. The mermaids.”

“Merpeople,” Derek corrected automatically.

“Right,” Stiles agreed enthusiastically, staring at Derek hopefully.

He shifted, watching Stiles uncertainly. “You wrote one of your papers on the merfolk?”

“Yeah,” Stiles said. He looked up at the ceiling and rattled off, “Physiological differences between the East and West Atlantic mermaids and the impact that makes on their breeding habits.”

Derek tilted his head. “Oh.” He had the merrow from the North Atlantic, and Lonnie was from the Caribbean. She was a good judge of character. He should introduce Stiles. “Okay.”

Stiles gave him a sheepish smile. “You know, Professor Fenris told me I should have contacted the marine biology department when I was working on my paper the first time around. Do you think we would have met?”

“Probably,” Derek said, half-smiling at the thought.

Stiles grinned. “Weird, huh? Do you think we still would have — you know?” He gestured between the two of them expansively.

Derek thought about it. “Probably not,” he admitted. “Not because of you but — well, if I’d met you as a student first, I don’t think so.”

“Oh.” Stiles’ face fell a little. “Is this…going to get weird?”

Derek shook his head. “You’re not in any of my classes,” he said. “Do you have a problem with it?”

“No,” Stiles said, a cheeky grin sneaking back onto his face. _“Professor.”_

Derek could feel his face heating up at the way Stiles said it, almost purring it. _Dirty._

Stiles’ grin widened. “We’re going to have fun later,” he promised Derek. “Er,” he added, eyes flickering to the clock on the microwave. “Much later. I gotta get going.” He levered himself upright with a wince and Derek stared at him, concerned.

“You okay?”

“Yeah,” Stiles smiled. “Fine, just a little sore. My ass took a pounding last night.”

Derek’s face went even hotter. “I’m sorry — “

Stiles shut him up with a kiss. “Don’t apologize,” he said gently. “I enjoyed every minute of it, okay? I’m looking forward to a repeat performance later — many, _many_ repeat performances.” He took a step backward. “I’ll see you around, okay?”

“Okay,” Derek breathed, watching him head for the front door. Stiles gave him one last wave before closing it behind himself. Derek touched his lips, still warm from Stiles’. “Okay,” he repeated to himself, a smile spreading across his face. “Okay.”


	5. Epilogue

Stiles trotted across campus, cheeks pink in the cool December air. It was the last week of classes and his Humanoid Anatomy and Physiology final was in less than an hour, but he had one stop to make first, ducking between buildings until he reached the research lab at the edge of campus, wrenching open one of the wooden doors and stepping inside the only slightly-warmer, somewhat fishy interior. He waved at Derek’s research assistant, Danny, who was up on a ladder fixing a light bulb.

Danny waved back, wobbling precariously at the top of the ladder, and called down to him, “Derek’s in his office with a student. He should be done soon.”

“Thanks!” Stiles called back, and slowed his pace, strolling casually down the long rows of massive tanks. He paused by Lonnie’s tank, smiling as she emerged from the thick seaweed to greet him, long fingers pressing up against the glass. Stiles’ smile widened as he remembered Derek introducing them, the care and excitement obvious in his voice as he said “This is Lonnie - _syreni solis,_ native to the Caribbean.” She’d been extremely patient, allowing Derek to show Stiles the way the spines on her head and back were able to extend and retract. Derek’s obvious enthusiasm for his research was a huge turn on for Stiles; he’d never seen Derek get more excited than when he was talking about the merfolk.

“What do you think?” Derek had asked, but he hadn’t been talking to Stiles — he’d been talking to Lonnie, who surprised him by replying in a flurry of hand gestures, which Derek had returned just as easily.

“Are you talking about me?” Stiles had asked accusingly, and Derek had turned to him with a smirk to say, “Lonnie thinks you’re a keeper.”

Now, Stiles knew just enough sign language to be able to sign _Hello, how are you?_ and he could understand _some_ of what Lonnie signed back. He had the feeling that she was dumbing down her signs for him, and he still could only understand her maybe a quarter of the time.

Down the hall, a girl came out of Derek’s office, calling a thank you over her shoulder as she shoved a handful of papers into her backpack. Stiles waited for her to pass by before he waved at Lonnie and headed down the quiet hall.

Derek had his head bent over the desk, making a few notes on a piece of paper, though he looked up and smiled faintly when Stiles leaned against the doorway. He was wearing the thick-rimmed glasses that Stiles like to say put him in professor mode, which was unfair because they intensified his attractiveness by like a thousand, and Stiles had definitely had some inappropriate fantasies about him — fantasies he fully intended to persuade Derek to make reality someday.

“Hey,” Derek said, shaking Stiles from his daydream. “Don’t you have an exam you should be attending?”

“Not for — ” Stiles checked the time on his phone. “Forty-five minutes.” He stepped into the office, dropping into one of the chairs across from Derek’s. He placed a paper bag on the desk between them. “Got you a snack.”

“Brownies from Blue Moon?” Derek asked, his smile widening.

“Using your super senses is cheating,” Stiles informed him, a little entranced by the way Derek’s eyes crinkled up at the corners when he smiled. Derek pulled the bag toward him, pulling out a slab of brownie. He split it in half, offering Stiles one piece, and Stiles took it gladly, grinning. “How are finals going?”

“One more this afternoon and that’s it,” Derek said, scowling as he dropped brownie crumbs all over the paperwork on his desk. “You?”

“Two finals today and then I’m free,” Stiles grinned.

Derek glanced up at him, his brow furrowing. “You still okay with coming tonight?”

Stiles shifted in his seat, a little nervous. “Yeah, totally,” he said. Derek’s frown deepened and Stiles added, “I mean, I’m nervous, but I’m excited to meet your family. I’ve just never been to an event so, uh, fancy before.” The Hale pack was hosting their yearly benefit for the National Park Service and the redwoods — or something like that, anyway; Stiles had been too overwhelmed by the invitation to quite follow most of what Derek had said. By all accounts — well, according to Lydia — it was one of _the_ events of the holiday season. Stiles had had to rent a _tuxedo._

Derek’s face softened. “I did invite you to dinner last weekend,” he pointed out, sounding faintly amused. “You didn’t have to plunge into the deep end like this.”

“I had to study,” Stiles complained. He added, smiling ruefully, “No better time to make a fool of myself then in front of a huge crowd of celebrities and your family, huh?”

Derek rolled his eyes. “As long as you don’t trip in front of the paparazzi you’ll be fine.”

“Oh, _that’s_ reassuring,” Stiles groaned. “Thanks a lot.”

“I’ll hold your hand,” Derek snorted. “Calm down.”

Stiles’ lips parted. “You — you will?”

It’d only been two months since that first time they’d fucked, barely a month since they’d started dating. Stiles had gotten to know Derek well enough in that time that he knew Derek liked to keep to himself, staying out his family’s limelight. Even for him to go to the benefit was big enough news, but that he’d asked Stiles to come with him as his date…Stiles knew that meant — it meant _something._ What, he wasn’t quite sure; trust, maybe. Derek’s pack — his family — was important to him, and to invite Stiles to meet them — well. Stiles couldn’t hold back the slow grin that split his face.

“I will,” Derek said, his tone gentling, the corners of his mouth curving upward.

“Thanks,” Stiles said softly.

Derek nodded, his face relaxing. “I think you have an exam to get to, don’t you?”

Stiles glanced at the time on his phone and sighed. “Yeah, probably.” He got to his feet slowly, stretching. “I’ll meet you back here after my last exam?” There wasn’t enough time to him to get home and change before the benefit began, so his tux and Derek’s were both hanging in the hall closet.

Derek nodded again, a faint smile returning to his lips. “See you then.”

Stiles grinned, blowing him a kiss as he left the office. He trotted out of the lab and across campus, ducking into the lecture hall where his first final of the day was to be held. Stiles dropped himself into a seat, tapping his foot impatiently as more students filtered in through the lecture hall doors. He was nervous to get start and nervous about tonight — his phone buzzed in his pocket and he jumped a little, startled. It was from Derek.

_You're going to do fine. We'll celebrate tonight._

Stiles grinned, feeling a little better. He jumped again as, from the front of the hall, Professor Fenris barked, "Phones away!"

He shoved his phone back in his pocket as the professor and TA moved up the rows of students, passing out the exam. When the papers were placed down in front of him, Stiles was startled to find it also contained his resubmitted paper on merpeople. He flipped to the back, a little nervous, and was elated to see _A. I'm impressed with your improvement, Mr. Stilinski. See what a little extra effort can do?_

A little smug on Fenris's part, but he'd take the A, pumping his fist into the air with a "Yessss!"

"Mr. Stilinski!" Fenris snapped.

Stiles dropped his arm, flushing a little. "Sorry," he mumbled, dropping his eyes to the final. The rush of enthusiasm from the good grade carried him through the exam — it was easy, _easy,_ and he breezed through it, right up until the final question: _What did you learn this semester?_

Stiles leaned back in his seat, tapping his pen against his teeth. He grinned wryly. Oh, where to _begin?_

**Author's Note:**

> Dubious consent warning goes both ways: Stiles is expecting to have his blood drawn by a vampire, not heat sexed up by a werewolf, but things move fast/he's not sure what's going on/not sure he wants to stop and never tells Derek no. Derek is in heat and mostly incapable of stopping himself. The incident is discussed/ruminated upon many times during the fic, and the possible dubious consented-ness is not glossed over or ignored. 
> 
> Thanks for reading! You can find us both online: Tsumi ([twitter](https://twitter.com/tsuminubiaru) • [tumblr](http://tsuminubiaru.tumblr.com/)) & Grimm ([twitter](https://twitter.com/Grimm_times) • [tumblr](http://coyotequeens.tumblr.com/))

**Works inspired by this one:**

  * [[Fanart] For Science!](https://archiveofourown.org/works/2199252) by [Tsuminoaru](https://archiveofourown.org/users/Tsuminoaru/pseuds/Tsuminoaru)




End file.
